diff --git a/media/ffvpx/libavcodec/dummy_funcs.c b/media/ffvpx/libavcodec/dummy_funcs.c
index 94404f9bb4..dba9da4dad 100644
--- a/media/ffvpx/libavcodec/dummy_funcs.c
+++ b/media/ffvpx/libavcodec/dummy_funcs.c
@@ -5,7 +5,9 @@
 
 #include "avcodec.h"
 
+typedef struct FFTContext FFTContext;
 typedef struct H264PredContext H264PredContext;
+typedef struct RDFTContext RDFTContext;
 typedef struct VideoDSPContext VideoDSPContext;
 typedef struct VP8DSPContext VP8DSPContext;
 typedef struct VP9DSPContext VP9DSPContext;
@@ -853,6 +855,11 @@ AVBitStreamFilter ff_noise_bsf;
 AVBitStreamFilter ff_remove_extradata_bsf;
 AVBitStreamFilter ff_text2movsub_bsf;
 
+void ff_fft_init_aarch64(FFTContext *s) {}
+void ff_fft_init_arm(FFTContext *s) {}
+void ff_fft_init_mips(FFTContext *s) {}
+void ff_fft_init_ppc(FFTContext *s) {}
+void ff_rdft_init_arm(RDFTContext *s) {}
 void ff_h264_pred_init_aarch64(H264PredContext *h, int codec_id,
                                const int bit_depth,
                                const int chroma_format_idc) {}
diff --git a/media/ffvpx/libavcodec/moz.build b/media/ffvpx/libavcodec/moz.build
index f3c7edb67c..738fe835d8 100644
--- a/media/ffvpx/libavcodec/moz.build
+++ b/media/ffvpx/libavcodec/moz.build
@@ -157,6 +157,13 @@ SOURCES += [
     'xiph.c'
 ]
 
+if CONFIG['MOZ_LIBAV_FFT']:
+    SOURCES += [
+        'avfft.c',
+        'fft_float.c',
+        'rdft.c',
+    ]
+
 SYMBOLS_FILE = 'avcodec.symbols'
 NO_VISIBILITY_FLAGS = True
 
diff --git a/media/ffvpx/libavcodec/x86/moz.build b/media/ffvpx/libavcodec/x86/moz.build
index 99b76894ac..9bafda725e 100644
--- a/media/ffvpx/libavcodec/x86/moz.build
+++ b/media/ffvpx/libavcodec/x86/moz.build
@@ -75,6 +75,12 @@ SOURCES += [
     'vp9mc_16bpp.asm',
 ]
 
+if CONFIG['MOZ_LIBAV_FFT']:
+    SOURCES += [
+        'fft.asm',
+        'fft_init.c',
+    ]
+
 FINAL_LIBRARY = 'mozavcodec'
 
 include('/media/ffvpx/ffvpxcommon.mozbuild')