diff --git a/lib/libutil/pw_util.c b/lib/libutil/pw_util.c
index 708583d05877..90c9d72f4f93 100644
--- a/lib/libutil/pw_util.c
+++ b/lib/libutil/pw_util.c
@@ -266,10 +266,11 @@ pw_mkdb(const char *user)
 		/* child */
 		if (user == NULL)
 			execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
-			    "-d", passwd_dir, tempname, NULL);
+			    "-d", passwd_dir, tempname, (char *)NULL);
 		else
 			execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
-			    "-d", passwd_dir, "-u", user, tempname, NULL);
+			    "-d", passwd_dir, "-u", user, tempname,
+			    (char *)NULL);
 		_exit(1);
 		/* NOTREACHED */
 	default:
@@ -321,7 +322,7 @@ pw_edit(int notsetuid)
 			(void)setuid(getuid());
 		}
 		errno = 0;
-		execlp(editor, basename(editor), tempname, NULL);
+		execlp(editor, basename(editor), tempname, (char *)NULL);
 		_exit(errno);
 	default:
 		/* parent */
diff --git a/usr.bin/m4/gnum4.c b/usr.bin/m4/gnum4.c
index 85a937c705bb..8940bb820f77 100644
--- a/usr.bin/m4/gnum4.c
+++ b/usr.bin/m4/gnum4.c
@@ -499,7 +499,7 @@ doesyscmd(const char *cmd)
 		(void) close(p[0]);
 		(void) dup2(p[1], 1);
 		(void) close(p[1]);
-		execl(_PATH_BSHELL, "sh", "-c", cmd, NULL);
+		execl(_PATH_BSHELL, "sh", "-c", cmd, (char *)NULL);
 		exit(1);
 	default:
 		/* Read result in two stages, since m4's buffer is