diff --git a/lib/commonio.c b/lib/commonio.c
index 6d744ad1..df2986aa 100644
--- a/lib/commonio.c
+++ b/lib/commonio.c
@@ -33,6 +33,7 @@
 #include "commonio.h"
 #include "shadowlog_internal.h"
 
+
 /* local function prototypes */
 static int lrename (const char *, const char *);
 static int check_link_count (const char *file, bool log);
@@ -354,33 +355,25 @@ bool commonio_present (const struct commonio_db *db)
 
 int commonio_lock_nowait (struct commonio_db *db, bool log)
 {
-	char* file = NULL;
-	char* lock = NULL;
-	size_t lock_file_len;
-	size_t file_len;
-	int err = 0;
+	int   err = 0;
+	char  *file = NULL;
+	char  *lock = NULL;
 
 	if (db->locked) {
 		return 1;
 	}
-	file_len = strlen(db->filename) + 11;/* %lu max size */
-	lock_file_len = strlen(db->filename) + 6; /* sizeof ".lock" */
-	file = MALLOC(file_len, char);
-	if (file == NULL) {
+
+	if (asprintf(&file, "%s.%ju", db->filename, (uintmax_t) getpid()) == -1)
 		goto cleanup_ENOMEM;
-	}
-	lock = MALLOC(lock_file_len, char);
-	if (lock == NULL) {
+	if (asprintf(&lock, "%s.lock", db->filename) == -1)
 		goto cleanup_ENOMEM;
-	}
-	snprintf (file, file_len, "%s.%lu",
-	          db->filename, (unsigned long) getpid ());
-	snprintf (lock, lock_file_len, "%s.lock", db->filename);
+
 	if (do_lock_file (file, lock, log) != 0) {
 		db->locked = true;
 		lock_count++;
 		err = 1;
 	}
+
 cleanup_ENOMEM:
 	free(file);
 	free(lock);
diff --git a/lib/copydir.c b/lib/copydir.c
index 36f2004d..d60cf535 100644
--- a/lib/copydir.c
+++ b/lib/copydir.c
@@ -208,11 +208,7 @@ static void remove_link (/*@only@*/struct link_name *ln)
 
 static /*@exposed@*/ /*@null@*/struct link_name *check_link (const char *name, const struct stat *sb)
 {
-	struct link_name *lp;
-	size_t src_len;
-	size_t dst_len;
-	size_t name_len;
-	size_t len;
+	struct link_name  *lp;
 
 	/* copy_tree () must be the entry point */
 	assert (NULL != src_orig);
@@ -229,15 +225,11 @@ static /*@exposed@*/ /*@null@*/struct link_name *check_link (const char *name, c
 	}
 
 	lp = XMALLOC(1, struct link_name);
-	src_len = strlen (src_orig);
-	dst_len = strlen (dst_orig);
-	name_len = strlen (name);
 	lp->ln_dev = sb->st_dev;
 	lp->ln_ino = sb->st_ino;
 	lp->ln_count = sb->st_nlink;
-	len = name_len - src_len + dst_len + 1;
-	lp->ln_name = XMALLOC(len, char);
-	(void) snprintf (lp->ln_name, len, "%s%s", dst_orig, name + src_len);
+	if (asprintf(&lp->ln_name, "%s%s", dst_orig, name + strlen(src_orig)) == -1)
+		exit(EXIT_FAILURE);
 	lp->ln_next = links;
 	links = lp;
 
@@ -314,8 +306,9 @@ static int copy_tree_impl (const struct path_info *src, const struct path_info *
 		set_orig = true;
 	}
 	while ((0 == err) && (ent = readdir (dir)) != NULL) {
-		char    *src_name, *dst_name;
-		size_t  src_len, dst_len;
+		char              *src_name = NULL;
+		char              *dst_name;
+		struct path_info  src_entry, dst_entry;
 		/*
 		 * Skip the "." and ".." entries
 		 */
@@ -325,26 +318,16 @@ static int copy_tree_impl (const struct path_info *src, const struct path_info *
 			continue;
 		}
 
-		src_len = strlen (ent->d_name) + 2;
-		dst_len = strlen (ent->d_name) + 2;
-		src_len += strlen (src->full_path);
-		dst_len += strlen (dst->full_path);
-
-		src_name = MALLOC(src_len, char);
-		dst_name = MALLOC(dst_len, char);
-
-		if ((NULL == src_name) || (NULL == dst_name)) {
+		if (asprintf(&src_name, "%s/%s", src->full_path, ent->d_name) == -1)
+		{
+			err = -1;
+			continue;
+		}
+		if (asprintf(&dst_name, "%s/%s", dst->full_path, ent->d_name) == -1)
+		{
 			err = -1;
 			goto skip;
 		}
-		/*
-		 * Build the filename for both the source and
-		 * the destination files.
-		 */
-		struct path_info src_entry, dst_entry;
-
-		(void) snprintf (src_name, src_len, "%s/%s", src->full_path, ent->d_name);
-		(void) snprintf (dst_name, dst_len, "%s/%s", dst->full_path, ent->d_name);
 
 		src_entry.full_path = src_name;
 		src_entry.dirfd = dirfd(dir);
@@ -356,9 +339,10 @@ static int copy_tree_impl (const struct path_info *src, const struct path_info *
 
 		err = copy_entry(&src_entry, &dst_entry, reset_selinux,
 				 old_uid, new_uid, old_gid, new_gid);
+
+		free(dst_name);
 skip:
-		free (src_name);
-		free (dst_name);
+		free(src_name);
 	}
 	(void) closedir (dir);
 	(void) close (dst_fd);
@@ -625,12 +609,11 @@ static int copy_symlink (const struct path_info *src, const struct path_info *ds
 	 * directory.
 	 */
 	if (strncmp (oldlink, src_orig, strlen (src_orig)) == 0) {
-		size_t len = strlen (dst_orig) + strlen (oldlink) - strlen (src_orig) + 1;
-		char *dummy = XMALLOC(len, char);
-		(void) snprintf (dummy, len, "%s%s",
-		                 dst_orig,
-		                 oldlink + strlen (src_orig));
-		free (oldlink);
+		char  *dummy;
+
+		if (asprintf(&dummy, "%s%s", dst_orig, oldlink + strlen(src_orig)) == -1)
+			exit(EXIT_FAILURE);
+		free(oldlink);
 		oldlink = dummy;
 	}
 
diff --git a/lib/env.c b/lib/env.c
index e4ccee3d..c9c03c9b 100644
--- a/lib/env.c
+++ b/lib/env.c
@@ -20,6 +20,8 @@
 #include "prototypes.h"
 #include "defines.h"
 #include "shadowlog.h"
+
+
 /*
  * NEWENVP_STEP must be a power of two.  This is the number
  * of (char *) pointers to allocate at a time, to avoid using
@@ -67,16 +69,12 @@ void initenv (void)
 
 void addenv (const char *string, /*@null@*/const char *value)
 {
-	char *cp, *newstring;
-	size_t i;
-	size_t n;
+	char    *cp, *newstring;
+	size_t  i, n;
 
 	if (NULL != value) {
-		size_t len = strlen (string) + strlen (value) + 2;
-		int wlen;
-		newstring = XMALLOC(len, char);
-		wlen = snprintf (newstring, len, "%s=%s", string, value);
-		assert (wlen == (int) len -1);
+		if (asprintf(&newstring, "%s=%s", string, value) == -1)
+			exit(EXIT_FAILURE);
 	} else {
 		newstring = xstrdup (string);
 	}
@@ -88,7 +86,7 @@ void addenv (const char *string, /*@null@*/const char *value)
 
 	cp = strchr (newstring, '=');
 	if (NULL == cp) {
-		free (newstring);
+		free(newstring);
 		return;
 	}
 
@@ -105,7 +103,7 @@ void addenv (const char *string, /*@null@*/const char *value)
 	}
 
 	if (i < newenvc) {
-		free (newenvp[i]);
+		free(newenvp[i]);
 		newenvp[i] = newstring;
 		return;
 	}
diff --git a/lib/getdef.c b/lib/getdef.c
index 7fe6cefb..585e8244 100644
--- a/lib/getdef.c
+++ b/lib/getdef.c
@@ -26,6 +26,7 @@
 #include "getdef.h"
 #include "shadowlog_internal.h"
 
+
 /*
  * A configuration item definition.
  */
@@ -444,21 +445,14 @@ out:
 void setdef_config_file (const char* file)
 {
 #ifdef USE_ECONF
-	size_t len;
-	char* cp;
+	char  *cp;
 
-	len = strlen(file) + strlen(sysconfdir) + 2;
-	cp = MALLOC(len, char);
-	if (cp == NULL)
-		exit (13);
-	snprintf(cp, len, "%s/%s", file, sysconfdir);
+	if (asprintf(&cp, "%s/%s", file, sysconfdir) == -1)
+		exit(13);
 	sysconfdir = cp;
 #ifdef VENDORDIR
-	len = strlen(file) + strlen(vendordir) + 2;
-	cp = MALLOC(len, char);
-	if (cp == NULL)
-		exit (13);
-	snprintf(cp, len, "%s/%s", file, vendordir);
+	if (asprintf(&cp, "%s/%s", file, vendordir) == -1)
+		exit(13);
 	vendordir = cp;
 #endif
 #else
diff --git a/lib/groupio.c b/lib/groupio.c
index abad2cbf..d9d9823b 100644
--- a/lib/groupio.c
+++ b/lib/groupio.c
@@ -22,6 +22,7 @@
 #include "getdef.h"
 #include "groupio.h"
 
+
 static /*@null@*/struct commonio_entry *merge_group_entries (
 	/*@null@*/ /*@returned@*/struct commonio_entry *gr1,
 	/*@null@*/struct commonio_entry *gr2);
@@ -300,12 +301,13 @@ static /*@null@*/struct commonio_entry *merge_group_entries (
 	/*@null@*/ /*@returned@*/struct commonio_entry *gr1,
 	/*@null@*/struct commonio_entry *gr2)
 {
-	struct group *gptr1;
-	struct group *gptr2;
-	char **new_members;
-	size_t members = 0;
-	char *new_line;
-	size_t new_line_len, i;
+	char          *new_line;
+	char          **new_members;
+	size_t        i;
+	size_t        members = 0;
+	struct group  *gptr1;
+	struct group  *gptr2;
+
 	if (NULL == gr2 || NULL == gr1) {
 		errno = EINVAL;
 		return NULL;
@@ -319,12 +321,8 @@ static /*@null@*/struct commonio_entry *merge_group_entries (
 	}
 
 	/* Concatenate the 2 lines */
-	new_line_len = strlen (gr1->line) + strlen (gr2->line) +1;
-	new_line = MALLOC(new_line_len + 1, char);
-	if (NULL == new_line) {
+	if (asprintf(&new_line, "%s\n%s", gr1->line, gr2->line) == -1)
 		return NULL;
-	}
-	snprintf(new_line, new_line_len + 1, "%s\n%s", gr1->line, gr2->line);
 
 	/* Concatenate the 2 list of members */
 	for (i=0; NULL != gptr1->gr_mem[i]; i++);
@@ -343,7 +341,7 @@ static /*@null@*/struct commonio_entry *merge_group_entries (
 	}
 	new_members = CALLOC (members + 1, char *);
 	if (NULL == new_members) {
-		free (new_line);
+		free(new_line);
 		return NULL;
 	}
 	for (i=0; NULL != gptr1->gr_mem[i]; i++) {
diff --git a/lib/mail.c b/lib/mail.c
index 304063f5..ede35f9e 100644
--- a/lib/mail.c
+++ b/lib/mail.c
@@ -35,22 +35,19 @@ void mailcheck (void)
 	 */
 	mailbox = getenv ("MAILDIR");
 	if (NULL != mailbox) {
-		char *newmail;
-		size_t len = strlen (mailbox) + 5;
-		int wlen;
+		char  *newmail;
 
-		newmail = XMALLOC(len, char);
-		wlen = snprintf (newmail, len, "%s/new", mailbox);
-		assert (wlen == (int) len - 1);
+		if (asprintf(&newmail, "%s/new", mailbox) == -1)
+			exit(EXIT_FAILURE);
 
 		if (stat (newmail, &statbuf) != -1 && statbuf.st_size != 0) {
 			if (statbuf.st_mtime > statbuf.st_atime) {
-				free (newmail);
+				free(newmail);
 				(void) puts (_("You have new mail."));
 				return;
 			}
 		}
-		free (newmail);
+		free(newmail);
 	}
 
 	mailbox = getenv ("MAIL");
diff --git a/lib/prefix_flag.c b/lib/prefix_flag.c
index adab9974..7e143307 100644
--- a/lib/prefix_flag.c
+++ b/lib/prefix_flag.c
@@ -29,6 +29,7 @@
 #include "getdef.h"
 #include "shadowlog.h"
 
+
 static char *passwd_db_file = NULL;
 static char *spw_db_file = NULL;
 static char *group_db_file = NULL;
@@ -104,50 +105,43 @@ extern const char* process_prefix_flag (const char* short_opt, int argc, char **
 				 log_get_progname());
 			exit (E_BAD_ARG);
 		}
-		size_t len;
-		len = strlen(prefix) + strlen(PASSWD_FILE) + 2;
-		passwd_db_file = XMALLOC(len, char);
-		snprintf(passwd_db_file, len, "%s/%s", prefix, PASSWD_FILE);
+
+		if (asprintf(&passwd_db_file, "%s/%s", prefix, PASSWD_FILE) == -1)
+			exit(EXIT_FAILURE);
 		pw_setdbname(passwd_db_file);
 
-		len = strlen(prefix) + strlen(GROUP_FILE) + 2;
-		group_db_file = XMALLOC(len, char);
-		snprintf(group_db_file, len, "%s/%s", prefix, GROUP_FILE);
+		if (asprintf(&group_db_file, "%s/%s", prefix, GROUP_FILE) == -1)
+			exit(EXIT_FAILURE);
 		gr_setdbname(group_db_file);
 
 #ifdef  SHADOWGRP
-		len = strlen(prefix) + strlen(SGROUP_FILE) + 2;
-		sgroup_db_file = XMALLOC(len, char);
-		snprintf(sgroup_db_file, len, "%s/%s", prefix, SGROUP_FILE);
+		if (asprintf(&sgroup_db_file, "%s/%s", prefix, SGROUP_FILE) == -1)
+			exit(EXIT_FAILURE);
 		sgr_setdbname(sgroup_db_file);
 #endif
 #ifdef	USE_NIS
 		__setspNIS(0); /* disable NIS for now, at least until it is properly supporting a "prefix" */
 #endif
 
-		len = strlen(prefix) + strlen(SHADOW_FILE) + 2;
-		spw_db_file = XMALLOC(len, char);
-		snprintf(spw_db_file, len, "%s/%s", prefix, SHADOW_FILE);
+		if (asprintf(&spw_db_file, "%s/%s", prefix, SHADOW_FILE) == -1)
+			exit(EXIT_FAILURE);
 		spw_setdbname(spw_db_file);
 
 #ifdef ENABLE_SUBIDS
-		len = strlen(prefix) + strlen("/etc/subuid") + 2;
-		suid_db_file = XMALLOC(len, char);
-		snprintf(suid_db_file, len, "%s/%s", prefix, "/etc/subuid");
+		if (asprintf(&suid_db_file, "%s/%s", prefix, "/etc/subuid") == -1)
+			exit(EXIT_FAILURE);
 		sub_uid_setdbname(suid_db_file);
 
-		len = strlen(prefix) + strlen("/etc/subgid") + 2;
-		sgid_db_file = XMALLOC(len, char);
-		snprintf(sgid_db_file, len, "%s/%s", prefix, "/etc/subgid");
+		if (asprintf(&sgid_db_file, "%s/%s", prefix, "/etc/subgid") == -1)
+			exit(EXIT_FAILURE);
 		sub_gid_setdbname(sgid_db_file);
 #endif
 
 #ifdef USE_ECONF
 		setdef_config_file(prefix);
 #else
-		len = strlen(prefix) + strlen("/etc/login.defs") + 2;
-		def_conf_file = XMALLOC(len, char);
-		snprintf(def_conf_file, len, "%s/%s", prefix, "/etc/login.defs");
+		if (asprintf(&def_conf_file, "%s/%s", prefix, "/etc/login.defs") == -1)
+			exit(EXIT_FAILURE);
 		setdef_config_file(def_conf_file);
 #endif
 	}
diff --git a/lib/run_part.c b/lib/run_part.c
index 3d0483d2..bd24d357 100644
--- a/lib/run_part.c
+++ b/lib/run_part.c
@@ -13,6 +13,7 @@
 #include "run_part.h"
 #include "shadowlog_internal.h"
 
+
 int run_part (char *script_path, const char *name, const char *action)
 {
 	int pid;
@@ -55,25 +56,22 @@ int run_parts (const char *directory, const char *name, const char *action)
 	}
 
 	for (n=0; n<scanlist; n++) {
-		int path_length;
-		struct stat sb;
+		char         *s;
+		struct stat  sb;
 
-		path_length=strlen(directory) + strlen(namelist[n]->d_name) + 2;
-		char *s = MALLOC(path_length, char);
-		if (!s) {
-			printf ("could not allocate memory\n");
+		if (asprintf(&s, "%s/%s", directory, namelist[n]->d_name) == -1) {
+			fprintf(stderr, "could not allocate memory\n");
 			for (; n<scanlist; n++) {
-				free (namelist[n]);
+				free(namelist[n]);
 			}
-			free (namelist);
+			free(namelist);
 			return (1);
 		}
-		snprintf (s, path_length, "%s/%s", directory, namelist[n]->d_name);
 
 		execute_result = 0;
 		if (stat (s, &sb) == -1) {
 			perror ("stat");
-			free (s);
+			free(s);
 			for (; n<scanlist; n++) {
 				free (namelist[n]);
 			}
@@ -85,7 +83,7 @@ int run_parts (const char *directory, const char *name, const char *action)
 			execute_result = run_part (s, name, action);
 		}
 
-		free (s);
+		free(s);
 
 		if (execute_result!=0) {
 			fprintf (shadow_logfd,
diff --git a/lib/setupenv.c b/lib/setupenv.c
index b433476c..654b7015 100644
--- a/lib/setupenv.c
+++ b/lib/setupenv.c
@@ -28,20 +28,18 @@
 #include "getdef.h"
 #include "shadowlog.h"
 
+
 #ifndef USE_PAM
 static void
 addenv_path (const char *varname, const char *dirname, const char *filename)
 {
-	char *buf;
-	size_t len = strlen (dirname) + strlen (filename) + 2;
-	int wlen;
+	char  *buf;
 
-	buf = XMALLOC(len, char);
-	wlen = snprintf (buf, len, "%s/%s", dirname, filename);
-	assert (wlen == (int) len - 1);
+	if (asprintf(&buf, "%s/%s", dirname, filename) == -1)
+		exit(EXIT_FAILURE);
 
 	addenv (varname, buf);
-	free (buf);
+	free(buf);
 }
 
 static void read_env_file (const char *filename)
diff --git a/src/useradd.c b/src/useradd.c
index fe62a051..3638211e 100644
--- a/src/useradd.c
+++ b/src/useradd.c
@@ -64,6 +64,7 @@
 #endif
 #include "shadowlog.h"
 
+
 #ifndef SKEL_DIR
 #define SKEL_DIR "/etc/skel"
 #endif
@@ -328,21 +329,14 @@ static void fail_exit (int code)
  */
 static void get_defaults (void)
 {
-	FILE *fp;
-	char *default_file = USER_DEFAULTS_FILE;
-	char buf[1024];
-	char *cp;
+	FILE  *fp;
+	char  *default_file = USER_DEFAULTS_FILE;
+	char  buf[1024];
+	char  *cp;
 
 	if (prefix[0]) {
-		size_t len;
-		int wlen;
-
-		len = strlen(prefix) + strlen(USER_DEFAULTS_FILE) + 2;
-		default_file = MALLOC(len, char);
-                if (default_file == NULL)
-                       return;
-		wlen = snprintf(default_file, len, "%s/%s", prefix, USER_DEFAULTS_FILE);
-		assert (wlen == (int) len -1);
+		if (asprintf(&default_file, "%s/%s", prefix, USER_DEFAULTS_FILE) == -1)
+			return;
 	}
 
 	/*
@@ -446,18 +440,13 @@ static void get_defaults (void)
 			}
 
 			if (prefix[0]) {
-				size_t len;
-				int wlen;
-				char* _def_template; /* avoid const warning */
+				char  *_def_template; /* avoid const warning */
 
-				len = strlen(prefix) + strlen(cp) + 2;
-				_def_template = XMALLOC(len, char);
-				wlen = snprintf(_def_template, len, "%s/%s", prefix, cp);
-				assert (wlen == (int) len -1);
+				if (asprintf(&_def_template, "%s/%s", prefix, cp) == -1)
+					exit(EXIT_FAILURE);
 				def_template = _def_template;
-			}
-			else {
-				def_template = xstrdup (cp);
+			} else {
+				def_template = xstrdup(cp);
 			}
 		}
 
@@ -469,19 +458,14 @@ static void get_defaults (void)
 				cp = USRSKELDIR;	/* XXX warning: const */
 			}
 
-			if(prefix[0]) {
-				size_t len;
-				int wlen;
-				char* _def_usrtemplate; /* avoid const warning */
+			if (prefix[0]) {
+				char  *_def_usrtemplate; /* avoid const warning */
 
-				len = strlen(prefix) + strlen(cp) + 2;
-				_def_usrtemplate = XMALLOC(len, char);
-				wlen = snprintf(_def_usrtemplate, len, "%s/%s", prefix, cp);
-				assert (wlen == (int) len -1);
+				if (asprintf(&_def_usrtemplate, "%s/%s", prefix, cp) == -1)
+					exit(EXIT_FAILURE);
 				def_usrtemplate = _def_usrtemplate;
-			}
-			else {
-				def_usrtemplate = xstrdup (cp);
+			} else {
+				def_usrtemplate = xstrdup(cp);
 			}
 		}
 		/*
@@ -560,32 +544,24 @@ static int set_defaults (void)
 	bool out_usrskel = false;
 	bool out_create_mail_spool = false;
 	bool out_log_init = false;
-	size_t len;
 	int ret = -1;
 
 
-	len = strlen(prefix) + strlen(NEW_USER_FILE) + 2;
-	new_file = MALLOC(len, char);
-        if (new_file == NULL) {
-		fprintf (stderr,
-		         _("%s: cannot create new defaults file: %s\n"),
-		         Prog, strerror(errno));
+	if (asprintf(&new_file, "%s%s%s", prefix, prefix[0]?"/":"", NEW_USER_FILE) == -1)
+	{
+		fprintf(stderr, _("%s: cannot create new defaults file: %s\n"),
+		        Prog, strerror(errno));
 		return -1;
         }
-	wlen = snprintf(new_file, len, "%s%s%s", prefix, prefix[0]?"/":"", NEW_USER_FILE);
-	assert (wlen <= (int) len -1);
 
 	if (prefix[0]) {
-		len = strlen(prefix) + strlen(USER_DEFAULTS_FILE) + 2;
-		default_file = MALLOC(len, char);
-		if (default_file == NULL) {
-			fprintf (stderr,
-			         _("%s: cannot create new defaults file: %s\n"),
-			         Prog, strerror(errno));
+		if (asprintf(&default_file, "%s/%s", prefix, USER_DEFAULTS_FILE) == -1)
+		{
+			fprintf(stderr,
+			        _("%s: cannot create new defaults file: %s\n"),
+			        Prog, strerror(errno));
 			goto setdef_err;
 		}
-		wlen = snprintf(default_file, len, "%s/%s", prefix, USER_DEFAULTS_FILE);
-		assert (wlen == (int) len -1);
 	}
 
 	new_file_dup = strdup(new_file);
@@ -1604,26 +1580,19 @@ static void process_flags (int argc, char **argv)
 			exit (E_BAD_ARG);
 		}
 		if (!dflg) {
-			char *uh;
-			size_t len = strlen (def_home) + strlen (user_name) + 2;
-			int wlen;
-
-			uh = XMALLOC(len, char);
-			wlen = snprintf (uh, len, "%s/%s", def_home, user_name);
-			assert (wlen == (int) len -1);
+			char  *uh;
 
+			if (asprintf(&uh, "%s/%s", def_home, user_name) == -1)
+				exit(EXIT_FAILURE);
 			user_home = uh;
 		}
 		if (prefix[0]) {
-			size_t len = strlen(prefix) + strlen(user_home) + 2;
-			int wlen;
-			char* _prefix_user_home; /* to avoid const warning */
-			_prefix_user_home = XMALLOC(len, char);
-			wlen = snprintf(_prefix_user_home, len, "%s/%s", prefix, user_home);
-			assert (wlen == (int) len -1);
-			prefix_user_home = _prefix_user_home;
-		}
-		else {
+			char  *p_u_h; /* to avoid const warning */
+
+			if (asprintf(&p_u_h, "%s/%s", prefix, user_home) == -1)
+				exit(EXIT_FAILURE);
+			prefix_user_home = p_u_h;
+		} else {
 			prefix_user_home = user_home;
 		}
 	}
diff --git a/src/userdel.c b/src/userdel.c
index f68b91ec..b2f64ea0 100644
--- a/src/userdel.c
+++ b/src/userdel.c
@@ -53,6 +53,7 @@
 #endif				/* ENABLE_SUBIDS */
 #include "shadowlog.h"
 
+
 /*
  * exit status values
  */
@@ -788,11 +789,9 @@ static int is_owner (uid_t uid, const char *path)
 
 static int remove_mailbox (void)
 {
-	const char *maildir;
-	char* mailfile;
-	int i;
-	int errors = 0;
-	size_t len;
+	int         i, errors = 0;
+	char        *mailfile;
+	const char  *maildir;
 
 	maildir = getdef_str ("MAIL_DIR");
 #ifdef MAIL_SPOOL_DIR
@@ -804,18 +803,13 @@ static int remove_mailbox (void)
 		return 0;
 	}
 
-	len = strlen (prefix) + strlen (maildir) + strlen (user_name) + 2;
-	mailfile = XMALLOC(len, char);
-
 	if (prefix[0]) {
-		(void) snprintf (mailfile, len, "%s/%s/%s",
-	    	             prefix, maildir, user_name);
+		if (asprintf(&mailfile, "%s/%s/%s", prefix, maildir, user_name) == -1)
+			exit(EXIT_FAILURE);
+	} else {
+		if (asprintf(&mailfile, "%s/%s", maildir, user_name) == -1)
+			exit(EXIT_FAILURE);
 	}
-	else {
-		(void) snprintf (mailfile, len, "%s/%s",
-	    	             maildir, user_name);
-	}
-	mailfile[len-1] = '\0';
 
 	if (access (mailfile, F_OK) != 0) {
 		if (ENOENT == errno) {
@@ -911,22 +905,19 @@ static int remove_mailbox (void)
 #ifdef WITH_TCB
 static int remove_tcbdir (const char *user_name, uid_t user_id)
 {
-	char *buf;
-	int ret = 0;
-	size_t buflen = (sizeof TCB_DIR) + strlen (user_name) + 2;
+	int   ret = 0;
+	char  *buf;
 
 	if (!getdef_bool ("USE_TCB")) {
 		return 0;
 	}
 
-	buf = MALLOC(buflen, char);
-	if (NULL == buf) {
-		fprintf (stderr, _("%s: Can't allocate memory, "
-		                   "tcb entry for %s not removed.\n"),
-		         Prog, user_name);
+	if (asprintf(&buf, TCB_DIR "/%s", user_name) == -1) {
+		fprintf(stderr,
+		        _("%s: Can't allocate memory, tcb entry for %s not removed.\n"),
+		        Prog, user_name);
 		return 1;
 	}
-	snprintf (buf, buflen, TCB_DIR "/%s", user_name);
 	if (shadowtcb_drop_priv () == SHADOWTCB_FAILURE) {
 		fprintf (stderr, _("%s: Cannot drop privileges: %s\n"),
 		         Prog, strerror (errno));
@@ -1128,15 +1119,10 @@ int main (int argc, char **argv)
 		user_gid = pwd->pw_gid;
 
 		if (prefix[0]) {
-
-			size_t len = strlen(prefix) + strlen(pwd->pw_dir) + 2;
-			int wlen;
-			user_home = XMALLOC(len, char);
-			wlen = snprintf(user_home, len, "%s/%s", prefix, pwd->pw_dir);
-			assert (wlen == (int) len -1);
-		}
-		else {
-			user_home = xstrdup (pwd->pw_dir);
+			if (asprintf(&user_home, "%s/%s", prefix, pwd->pw_dir) == -1)
+				exit(EXIT_FAILURE);
+		} else {
+			user_home = xstrdup(pwd->pw_dir);
 		}
 		pw_close();
 	}
diff --git a/src/usermod.c b/src/usermod.c
index 7d9e661d..693c94a3 100644
--- a/src/usermod.c
+++ b/src/usermod.c
@@ -59,6 +59,7 @@
 #endif
 #include "shadowlog.h"
 
+
 /*
  * exit status values
  * for E_GRP_UPDATE and E_NOSPACE (not used yet), other update requests
@@ -1265,16 +1266,14 @@ static void process_flags (int argc, char **argv)
 		user_newgid = user_gid;
 	}
 	if (prefix[0]) {
-		size_t len = strlen(prefix) + strlen(user_home) + 2;
-		int wlen;
-		prefix_user_home = XMALLOC(len, char);
-		wlen = snprintf(prefix_user_home, len, "%s/%s", prefix, user_home);
-		assert (wlen == (int) len -1);
+		if (asprintf(&prefix_user_home, "%s/%s", prefix, user_home) == -1)
+			exit(EXIT_FAILURE);
 		if (user_newhome) {
-			len = strlen(prefix) + strlen(user_newhome) + 2;
-			prefix_user_newhome = XMALLOC(len, char);
-			wlen = snprintf(prefix_user_newhome, len, "%s/%s", prefix, user_newhome);
-			assert (wlen == (int) len -1);
+			if (asprintf(&prefix_user_newhome, "%s/%s",
+			             prefix, user_newhome) == -1)
+			{
+				exit(EXIT_FAILURE);
+			}
 		}
 
 	}
@@ -2042,11 +2041,10 @@ static void update_faillog (void)
  */
 static void move_mailbox (void)
 {
-	const char *maildir;
-	char* mailfile;
-	int fd;
-	struct stat st;
-	size_t size;
+	int          fd;
+	char         *mailfile;
+	const char   *maildir;
+	struct stat  st;
 
 	maildir = getdef_str ("MAIL_DIR");
 #ifdef MAIL_SPOOL_DIR
@@ -2057,8 +2055,6 @@ static void move_mailbox (void)
 	if (NULL == maildir) {
 		return;
 	}
-	size = strlen(prefix) + strlen(maildir) + strlen(user_name) + 3;
-	mailfile = XMALLOC(size, char);
 
 	/*
 	 * O_NONBLOCK is to make sure open won't hang on mandatory locks.
@@ -2067,12 +2063,11 @@ static void move_mailbox (void)
 	 * between stat and chown).  --marekm
 	 */
 	if (prefix[0]) {
-		(void) snprintf (mailfile, size, "%s/%s/%s",
-	    	             prefix, maildir, user_name);
-	}
-	else {
-		(void) snprintf (mailfile, size, "%s/%s",
-	    	             maildir, user_name);
+		if (asprintf(&mailfile, "%s/%s/%s", prefix, maildir, user_name) == -1)
+			exit(EXIT_FAILURE);
+	} else {
+		if (asprintf(&mailfile, "%s/%s", maildir, user_name) == -1)
+			exit(EXIT_FAILURE);
 	}
 
 	fd = open (mailfile, O_RDONLY | O_NONBLOCK, 0);
@@ -2114,18 +2109,17 @@ static void move_mailbox (void)
 	(void) close (fd);
 
 	if (lflg) {
-		char* newmailfile;
-		size_t newsize;
+		char  *newmailfile;
 
-		newsize = strlen(prefix) + strlen(maildir) + strlen(user_newname) + 3;
-		newmailfile = XMALLOC(newsize, char);
 		if (prefix[0]) {
-			(void) snprintf (newmailfile, newsize, "%s/%s/%s",
-			                 prefix, maildir, user_newname);
-		}
-		else {
-			(void) snprintf (newmailfile, newsize, "%s/%s",
-			                 maildir, user_newname);
+			if (asprintf(&newmailfile, "%s/%s/%s",
+			             prefix, maildir, user_newname) == -1)
+			{
+				exit(EXIT_FAILURE);
+			}
+		} else {
+			if (asprintf(&newmailfile, "%s/%s", maildir, user_newname) == -1)
+				exit(EXIT_FAILURE);
 		}
 		if (   (link (mailfile, newmailfile) != 0)
 		    || (unlink (mailfile) != 0)) {
diff --git a/src/vipw.c b/src/vipw.c
index 6a980625..78d8314c 100644
--- a/src/vipw.c
+++ b/src/vipw.c
@@ -44,6 +44,7 @@
 #endif				/* WITH_TCB */
 #include "shadowlog.h"
 
+
 #define MSG_WARN_EDIT_OTHER_FILE _( \
 	"You have modified %s.\n"\
 	"You may need to modify %s for consistency.\n"\
@@ -192,16 +193,15 @@ static void vipwexit (const char *msg, int syserr, int ret)
 static void
 vipwedit (const char *file, int (*file_lock) (void), int (*file_unlock) (void))
 {
-	const char *editor;
-	pid_t pid;
-	struct stat st1, st2;
-	int status;
-	FILE *f;
-	pid_t orig_pgrp, editor_pgrp = -1;
-	sigset_t mask, omask;
+	int          status;
+	char         *to_rename;
+	FILE         *f;
+	pid_t        pid, orig_pgrp, editor_pgrp = -1;
+	sigset_t     mask, omask;
+	const char   *editor;
+	struct stat  st1, st2;
 	/* FIXME: the following should have variable sizes */
-	char filebackup[1024], fileedit[1024];
-	char *to_rename;
+	char         filebackup[1024], fileedit[1024];
 
 	snprintf (filebackup, sizeof filebackup, "%s-", file);
 #ifdef WITH_TCB
@@ -294,7 +294,7 @@ vipwedit (const char *file, int (*file_lock) (void), int (*file_unlock) (void))
 	} else if (0 == pid) {
 		/* use the system() call to invoke the editor so that it accepts
 		   command line args in the EDITOR and VISUAL environment vars */
-		char *buf;
+		char  *buf;
 
 		/* Wait for parent to make us the foreground pgrp. */
 		if (orig_pgrp != -1) {
@@ -304,9 +304,9 @@ vipwedit (const char *file, int (*file_lock) (void), int (*file_unlock) (void))
 				continue;
 		}
 
-		buf = MALLOC(strlen(editor) + strlen(fileedit) + 2, char);
-		snprintf (buf, strlen (editor) + strlen (fileedit) + 2,
-		          "%s %s", editor, fileedit);
+		if (asprintf(&buf, "%s %s", editor, fileedit) == -1)
+			exit(EXIT_FAILURE);
+
 		status = system (buf);
 		if (-1 == status) {
 			fprintf (stderr, _("%s: %s: %s\n"), Prog, editor,
@@ -420,13 +420,11 @@ vipwedit (const char *file, int (*file_lock) (void), int (*file_unlock) (void))
 		if (stat (file, &st1) != 0) {
 			vipwexit (_("failed to stat edited file"), errno, 1);
 		}
-		to_rename = MALLOC(strlen(file) + 2, char);
-		if (NULL == to_rename) {
-			vipwexit (_("failed to allocate memory"), errno, 1);
-		}
-		snprintf (to_rename, strlen (file) + 2, "%s+", file);
+		if (asprintf(&to_rename, "%s+", file) == -1)
+			vipwexit (_("asprintf(3) failed"), errno, 1);
+
 		if (create_backup_file (f, to_rename, &st1) != 0) {
-			free (to_rename);
+			free(to_rename);
 			vipwexit (_("failed to create backup file"), errno, 1);
 		}
 		(void) fclose (f);
@@ -444,7 +442,7 @@ vipwedit (const char *file, int (*file_lock) (void), int (*file_unlock) (void))
 		         Prog, file, strerror (errno), to_rename);
 #ifdef WITH_TCB
 		if (tcb_mode) {
-			free (to_rename);
+			free(to_rename);
 		}
 #endif				/* WITH_TCB */
 		vipwexit (0, 0, 1);
@@ -452,7 +450,7 @@ vipwedit (const char *file, int (*file_lock) (void), int (*file_unlock) (void))
 
 #ifdef WITH_TCB
 	if (tcb_mode) {
-		free (to_rename);
+		free(to_rename);
 		if (shadowtcb_gain_priv () == SHADOWTCB_FAILURE) {
 			vipwexit (_("failed to gain privileges"), errno, 1);
 		}