diff --git a/options/path.c b/options/path.c
index 17d6245582..304f009167 100644
--- a/options/path.c
+++ b/options/path.c
@@ -155,11 +155,11 @@ char *mp_splitext(const char *path, bstr *root)
 {
     assert(path);
     const char *split = strrchr(path, '.');
-    if (!split)
-        split = path + strlen(path);
+    if (!split || !split[1] || strchr(split, '/'))
+        return NULL;
     if (root)
-        *root = (bstr){.start = (char *)path, .len = path - split};
-    return (char *)split;
+        *root = (bstr){(char *)path, split - path};
+    return (char *)split + 1;
 }
 
 char *mp_path_join(void *talloc_ctx, struct bstr p1, struct bstr p2)
diff --git a/options/path.h b/options/path.h
index 0e1744bbd0..4756379fa2 100644
--- a/options/path.h
+++ b/options/path.h
@@ -50,10 +50,10 @@ char *mp_get_user_path(void *talloc_ctx, struct mpv_global *global,
 
 char *mp_basename(const char *path);
 
-/* Return file extension, including the '.'. If root is not NULL, set it to the
- * part of the path without extension. So: path == root + returnvalue
+/* Return file extension, excluding the '.'. If root is not NULL, set it to the
+ * part of the path without extension. So: path == root + "." + extension
  * Don't consider it a file extension if the only '.' is the first character.
- * Return "" if no extension.
+ * Return NULL if no extension and don't set *root in this case.
  */
 char *mp_splitext(const char *path, bstr *root);
 
diff --git a/player/screenshot.c b/player/screenshot.c
index 7336c64e97..500960aee4 100644
--- a/player/screenshot.c
+++ b/player/screenshot.c
@@ -347,7 +347,7 @@ void screenshot_to_file(struct MPContext *mpctx, const char *filename, int mode,
     }
     char *ext = mp_splitext(filename, NULL);
     if (ext)
-        opts.format = ext + 1; // omit '.'
+        opts.format = ext;
     struct mp_image *image = screenshot_get(mpctx, mode);
     if (!image) {
         screenshot_msg(ctx, SMSG_ERR, "Taking screenshot failed.");