diff --git a/lib/nss.c b/lib/nss.c
index 96364b76..02742902 100644
--- a/lib/nss.c
+++ b/lib/nss.c
@@ -38,7 +38,7 @@ static void nss_exit(void) {
 }
 
 // nsswitch_path is an argument only to support testing.
-void nss_init(char *nsswitch_path) {
+void nss_init(const char *nsswitch_path) {
 	FILE *nssfp = NULL;
 	char *line = NULL, *p, *token, *saveptr;
 	size_t len = 0;
diff --git a/lib/prototypes.h b/lib/prototypes.h
index 43f0cf1d..cd873bf7 100644
--- a/lib/prototypes.h
+++ b/lib/prototypes.h
@@ -242,7 +242,7 @@ extern /*@null@*//*@only@*/struct passwd *get_my_pwent (void);
 
 /* nss.c */
 #include <libsubid/subid.h>
-extern void nss_init(char *nsswitch_path);
+extern void nss_init(const char *nsswitch_path);
 extern bool nss_is_initialized(void);
 
 struct subid_nss_ops {
diff --git a/libmisc/idmapping.h b/libmisc/idmapping.h
index e3527606..81a628b8 100644
--- a/libmisc/idmapping.h
+++ b/libmisc/idmapping.h
@@ -17,7 +17,5 @@ extern struct map_range *get_map_ranges(int ranges, int argc, char **argv);
 extern void write_mapping(int proc_dir_fd, int ranges,
 	struct map_range *mappings, const char *map_file, uid_t ruid);
 
-extern void nss_init(char *nsswitch_path);
-
 #endif /* _ID_MAPPING_H_ */