diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
index e60b0247bc..185ba8df00 100644
--- a/libavfilter/avfilter.c
+++ b/libavfilter/avfilter.c
@@ -1304,8 +1304,6 @@ static int forward_status_change(AVFilterContext *filter, AVFilterLink *in)
     return 0;
 }
 
-#define FFERROR_NOT_READY FFERRTAG('N','R','D','Y')
-
 static int ff_filter_activate_default(AVFilterContext *filter)
 {
     unsigned i;
diff --git a/libavfilter/filters.h b/libavfilter/filters.h
index 2c78d60e62..370d99b38b 100644
--- a/libavfilter/filters.h
+++ b/libavfilter/filters.h
@@ -27,6 +27,11 @@
 
 #include "avfilter.h"
 
+/**
+ * Special return code when activate() did not do anything.
+ */
+#define FFERROR_NOT_READY FFERRTAG('N','R','D','Y')
+
 /**
  * Mark a filter ready and schedule it for activation.
  *