diff --git a/libavutil/tx.h b/libavutil/tx.h
index d6cdfdf9f20b3c7ac12a7dea69db28d23e10ac81..8b405c00214afed91c116e44758d1f57bfb617f2 100644
--- a/libavutil/tx.h
+++ b/libavutil/tx.h
@@ -35,7 +35,7 @@ typedef struct AVComplexDouble {
 enum AVTXType {
     /**
      * Standard complex to complex FFT with sample data type AVComplexFloat.
-     * Scaling currently unsupported
+     * Output is not 1/len normalized. Scaling currently unsupported.
      */
     AV_TX_FLOAT_FFT = 0,
     /**