diff --git a/libavcodec/arm/fft_neon.S b/libavcodec/arm/fft_neon.S
index 72431535d8..1db7abd146 100644
--- a/libavcodec/arm/fft_neon.S
+++ b/libavcodec/arm/fft_neon.S
@@ -4,6 +4,9 @@
  * Copyright (c) 2009 Mans Rullgard <mans@mansr.com>
  * Copyright (c) 2009 Naotoshi Nojiri
  *
+ * This algorithm (though not any of the implementation details) is
+ * based on libdjbfft by D. J. Bernstein.
+ *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
diff --git a/libavcodec/ppc/fft_altivec_s.S b/libavcodec/ppc/fft_altivec_s.S
index d17d033bab..5d3c5406c3 100644
--- a/libavcodec/ppc/fft_altivec_s.S
+++ b/libavcodec/ppc/fft_altivec_s.S
@@ -2,6 +2,9 @@
  * FFT transform with Altivec optimizations
  * Copyright (c) 2009 Loren Merritt
  *
+ * This algorithm (though not any of the implementation details) is
+ * based on libdjbfft by D. J. Bernstein.
+ *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
diff --git a/libavcodec/x86/fft_mmx.asm b/libavcodec/x86/fft_mmx.asm
index ea78396e7c..23a360fa68 100644
--- a/libavcodec/x86/fft_mmx.asm
+++ b/libavcodec/x86/fft_mmx.asm
@@ -2,6 +2,9 @@
 ;* FFT transform with SSE/3DNow optimizations
 ;* Copyright (c) 2008 Loren Merritt
 ;*
+;* This algorithm (though not any of the implementation details) is
+;* based on libdjbfft by D. J. Bernstein.
+;*
 ;* This file is part of FFmpeg.
 ;*
 ;* FFmpeg is free software; you can redistribute it and/or