diff --git a/libavcodec/x86/dcadsp_init.c b/libavcodec/x86/dcadsp_init.c
index bc94b44376..5975feefa6 100644
--- a/libavcodec/x86/dcadsp_init.c
+++ b/libavcodec/x86/dcadsp_init.c
@@ -82,6 +82,10 @@ SYNTH_FILTER_FUNC(sse)
 #endif
 SYNTH_FILTER_FUNC(sse2)
 SYNTH_FILTER_FUNC(avx)
+static void synth_filter_fma3(FFTContext *imdct,
+                             float *synth_buf_ptr, int *synth_buf_offset,
+                             float synth_buf2[32], const float window[512],
+                             float out[32], const float in[32], float scale);
 #if HAVE_FMA3_EXTERNAL
 SYNTH_FILTER_FUNC(fma3)
 #endif