diff --git a/subprojects/gstreamer/libs/gst/base/gsttypefindhelper.c b/subprojects/gstreamer/libs/gst/base/gsttypefindhelper.c
index 455b22911e..500ea355f8 100644
--- a/subprojects/gstreamer/libs/gst/base/gsttypefindhelper.c
+++ b/subprojects/gstreamer/libs/gst/base/gsttypefindhelper.c
@@ -579,6 +579,14 @@ buf_helper_find_suggest (gpointer data, guint probability, GstCaps * caps)
   }
 }
 
+static guint64
+buf_helper_get_length (gpointer data)
+{
+  GstTypeFindBufHelper *helper = (GstTypeFindBufHelper *) data;
+
+  return helper->size;
+}
+
 /**
  * gst_type_find_helper_for_data:
  * @obj: (nullable): object doing the typefinding, or %NULL (used for logging)
@@ -670,7 +678,7 @@ gst_type_find_helper_for_data_with_extension (GstObject * obj,
   find.data = &helper;
   find.peek = buf_helper_find_peek;
   find.suggest = buf_helper_find_suggest;
-  find.get_length = NULL;
+  find.get_length = buf_helper_get_length;
 
   type_list = gst_type_find_factory_get_list ();
   type_list = prioritize_extension (obj, type_list, extension);