diff --git a/libavcodec/opus.h b/libavcodec/opus.h
index 283d9d9f7a..80d685d47c 100644
--- a/libavcodec/opus.h
+++ b/libavcodec/opus.h
@@ -25,16 +25,10 @@
 
 #include <stdint.h>
 
-#include "avcodec.h"
-#include "opus_rc.h"
-
 #define MAX_FRAME_SIZE               1275
 #define MAX_FRAMES                   48
 #define MAX_PACKET_DUR               5760
 
-#define SILK_HISTORY                 322
-#define SILK_MAX_LPC                 16
-
 #define OPUS_TS_HEADER     0x7FE0        // 0x3ff (11 bits)
 #define OPUS_TS_MASK       0xFFE0        // top 11 bits
 
@@ -62,19 +56,4 @@ enum OpusBandwidth {
     OPUS_BANDWITH_NB
 };
 
-typedef struct SilkContext SilkContext;
-
-int ff_silk_init(AVCodecContext *avctx, SilkContext **ps, int output_channels);
-void ff_silk_free(SilkContext **ps);
-void ff_silk_flush(SilkContext *s);
-
-/**
- * Decode the LP layer of one Opus frame (which may correspond to several SILK
- * frames).
- */
-int ff_silk_decode_superframe(SilkContext *s, OpusRangeCoder *rc,
-                              float *output[2],
-                              enum OpusBandwidth bandwidth, int coded_channels,
-                              int duration_ms);
-
 #endif /* AVCODEC_OPUS_H */
diff --git a/libavcodec/opus_silk.c b/libavcodec/opus_silk.c
index fd1e83659c..cf8b16acff 100644
--- a/libavcodec/opus_silk.c
+++ b/libavcodec/opus_silk.c
@@ -28,6 +28,8 @@
 
 #include "mathops.h"
 #include "opus.h"
+#include "opus_rc.h"
+#include "opus_silk.h"
 #include "opustab.h"
 
 #define ROUND_MULL(a,b,s) (((MUL64(a, b) >> ((s) - 1)) + 1) >> 1)
diff --git a/libavcodec/opus_silk.h b/libavcodec/opus_silk.h
new file mode 100644
index 0000000000..6552c166a4
--- /dev/null
+++ b/libavcodec/opus_silk.h
@@ -0,0 +1,48 @@
+/*
+ * Opus Silk functions/definitions
+ * Copyright (c) 2012 Andrew D'Addesio
+ * Copyright (c) 2013-2014 Mozilla Corporation
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVCODEC_OPUS_SILK_H
+#define AVCODEC_OPUS_SILK_H
+
+#include "avcodec.h"
+#include "opus.h"
+#include "opus_rc.h"
+
+#define SILK_HISTORY                 322
+#define SILK_MAX_LPC                 16
+
+typedef struct SilkContext SilkContext;
+
+int ff_silk_init(AVCodecContext *avctx, SilkContext **ps, int output_channels);
+void ff_silk_free(SilkContext **ps);
+void ff_silk_flush(SilkContext *s);
+
+/**
+ * Decode the LP layer of one Opus frame (which may correspond to several SILK
+ * frames).
+ */
+int ff_silk_decode_superframe(SilkContext *s, OpusRangeCoder *rc,
+                              float *output[2],
+                              enum OpusBandwidth bandwidth, int coded_channels,
+                              int duration_ms);
+
+#endif /* AVCODEC_OPUS_SILK_H */
diff --git a/libavcodec/opusdec.c b/libavcodec/opusdec.c
index e26ca0b2c3..c5f06e0600 100644
--- a/libavcodec/opusdec.c
+++ b/libavcodec/opusdec.c
@@ -53,6 +53,8 @@
 #include "opustab.h"
 #include "opus_celt.h"
 #include "opus_parse.h"
+#include "opus_rc.h"
+#include "opus_silk.h"
 
 static const uint16_t silk_frame_duration_ms[16] = {
     10, 20, 40, 60,
diff --git a/libavcodec/opusenc_utils.h b/libavcodec/opusenc_utils.h
index be82e13767..c76295979a 100644
--- a/libavcodec/opusenc_utils.h
+++ b/libavcodec/opusenc_utils.h
@@ -22,6 +22,9 @@
 #ifndef AVCODEC_OPUSENC_UTILS_H
 #define AVCODEC_OPUSENC_UTILS_H
 
+#include <math.h>
+#include <string.h>
+
 #include "opus.h"
 
 typedef struct FFBesselFilter {
