diff --git a/src/usermod.c b/src/usermod.c
index f8896984..443f7b57 100644
--- a/src/usermod.c
+++ b/src/usermod.c
@@ -33,6 +33,7 @@
 #include <time.h>
 
 #include "alloc.h"
+#include "atoi/a2i.h"
 #include "atoi/str2i.h"
 #include "chkname.h"
 #include "defines.h"
@@ -302,35 +303,25 @@ struct ulong_range
 
 static struct ulong_range getulong_range(const char *str)
 {
-	struct ulong_range result = { .first = ULONG_MAX, .last = 0 };
-	long long first, last;
-	char *pos;
-
-	errno = 0;
-	first = strtoll(str, &pos, 10);
-	if (('\0' == *str) || ('-' != *pos ) || (0 != errno) ||
-	    (first != (unsigned long)first))
-		goto out;
-
-	errno = 0;
-	last = strtoll(pos + 1, &pos, 10);
-	if (('\0' != *pos ) || (0 != errno) ||
-	    (last != (unsigned long)last))
-		goto out;
-
-	if (first > last)
-		goto out;
+	char                *pos;
+	unsigned long       first, last;
+	struct ulong_range  result = { .first = ULONG_MAX, .last = 0 };
 
 	/*
 	 * uid_t in linux is an unsigned int, anything over this is an invalid
 	 * range will be later refused anyway by get_map_ranges().
 	 */
-	if (first > UINT_MAX || last > UINT_MAX)
-		goto out;
+	if (a2ul(&first, str, &pos, 10, 0, UINT_MAX) == -1 && errno != ENOTSUP)
+		return result;
 
-	result.first = (unsigned long)first;
-	result.last = (unsigned long)last;
-out:
+	if ('-' != *pos++)
+		return result;
+
+	if (a2ul(&last, pos, NULL, 10, first, UINT_MAX) == -1)
+		return result;
+
+	result.first = first;
+	result.last = last;
 	return result;
 }