diff --git a/src/tuxpaint.c b/src/tuxpaint.c
index 442bc7947..45a84a7b5 100644
--- a/src/tuxpaint.c
+++ b/src/tuxpaint.c
@@ -208,7 +208,10 @@ char *strcasestr(const char *haystack, const char *needle)
 
   result = strstr(uphaystack, upneedle);
 
-  return (result - uphaystack + (char *) haystack);
+  if (result != NULL)
+    return (result - uphaystack + (char *) haystack);
+  else
+    return NULL;
 }
 
 #endif