diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
index e96c8f2381..c441629d96 100644
--- a/libavfilter/avfilter.c
+++ b/libavfilter/avfilter.c
@@ -456,28 +456,28 @@ static const char *default_filter_name(void *filter_ctx)
 static void *filter_child_next(void *obj, void *prev)
 {
     AVFilterContext *ctx = obj;
-    if (!prev && ctx->filter && ctx->filter->priv_class)
+    if (!prev && ctx->filter && ctx->filter->priv_class && ctx->priv)
         return ctx->priv;
     return NULL;
 }
 
 static const AVClass *filter_child_class_next(const AVClass *prev)
 {
-    AVFilter **filter_ptr = NULL;
+    AVFilter **f = NULL;
 
     /* find the filter that corresponds to prev */
-    while (prev && *(filter_ptr = av_filter_next(filter_ptr)))
-        if ((*filter_ptr)->priv_class == prev)
+    while (prev && *(f = av_filter_next(f)))
+        if ((*f)->priv_class == prev)
             break;
 
     /* could not find filter corresponding to prev */
-    if (prev && !(*filter_ptr))
+    if (prev && !(*f))
         return NULL;
 
     /* find next filter with specific options */
-    while (*(filter_ptr = av_filter_next(filter_ptr)))
-        if ((*filter_ptr)->priv_class)
-            return (*filter_ptr)->priv_class;
+    while (*(f = av_filter_next(f)))
+        if ((*f)->priv_class)
+            return (*f)->priv_class;
     return NULL;
 }