1 files changed, 1 insertions, 1 deletions
diff --git a/src/main.c b/src/main.c
index 9bec0c8..e329e4e 100644
--- a/src/main.c
+++ b/src/main.c
@@ -351,7 +351,7 @@ void check_options (void)
     if ( !(m4 = getenv("M4"))) {
 	    char *slash;
 		m4 = M4;
-		if (slash = strrchr(M4, '/')) {
+		if ((slash = strrchr(M4, '/')) != NULL) {
 			m4 = slash+1;
 			/* break up $PATH */
 			const char *path = getenv("PATH");