diff --git a/vp9/decoder/vp9_decodeframe.h b/vp9/decoder/vp9_decodeframe.h
index 7245a9845..4537bc824 100644
--- a/vp9/decoder/vp9_decodeframe.h
+++ b/vp9/decoder/vp9_decodeframe.h
@@ -12,10 +12,18 @@
 #ifndef VP9_DECODER_VP9_DECODEFRAME_H_
 #define VP9_DECODER_VP9_DECODEFRAME_H_
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 struct VP9Common;
 struct VP9Decompressor;
 
 void vp9_init_dequantizer(struct VP9Common *cm);
 int vp9_decode_frame(struct VP9Decompressor *cpi, const uint8_t **p_data_end);
 
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
 #endif  // VP9_DECODER_VP9_DECODEFRAME_H_
diff --git a/vp9/decoder/vp9_decodemv.h b/vp9/decoder/vp9_decodemv.h
index 95272bfb3..539c9840e 100644
--- a/vp9/decoder/vp9_decodemv.h
+++ b/vp9/decoder/vp9_decodemv.h
@@ -14,10 +14,18 @@
 #include "vp9/decoder/vp9_onyxd_int.h"
 #include "vp9/decoder/vp9_reader.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 struct TileInfo;
 
 void vp9_read_mode_info(VP9_COMMON *cm, MACROBLOCKD *xd,
                         const struct TileInfo *const tile,
                         int mi_row, int mi_col, vp9_reader *r);
 
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
 #endif  // VP9_DECODER_VP9_DECODEMV_H_
diff --git a/vp9/decoder/vp9_detokenize.h b/vp9/decoder/vp9_detokenize.h
index 1780a0fb5..ce3d7653d 100644
--- a/vp9/decoder/vp9_detokenize.h
+++ b/vp9/decoder/vp9_detokenize.h
@@ -15,8 +15,16 @@
 #include "vp9/decoder/vp9_onyxd_int.h"
 #include "vp9/decoder/vp9_reader.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 int vp9_decode_block_tokens(VP9_COMMON *cm, MACROBLOCKD *xd,
                             int plane, int block, BLOCK_SIZE plane_bsize,
                             int x, int y, TX_SIZE tx_size, vp9_reader *r);
 
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
 #endif  // VP9_DECODER_VP9_DETOKENIZE_H_
diff --git a/vp9/decoder/vp9_dsubexp.h b/vp9/decoder/vp9_dsubexp.h
index 137f546b8..436f434fb 100644
--- a/vp9/decoder/vp9_dsubexp.h
+++ b/vp9/decoder/vp9_dsubexp.h
@@ -14,6 +14,14 @@
 
 #include "vp9/decoder/vp9_reader.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 void vp9_diff_update_prob(vp9_reader *r, vp9_prob* p);
 
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
 #endif  // VP9_DECODER_VP9_DSUBEXP_H_
diff --git a/vp9/decoder/vp9_onyxd.h b/vp9/decoder/vp9_onyxd.h
index a4b9c24fc..0fc9d578b 100644
--- a/vp9/decoder/vp9_onyxd.h
+++ b/vp9/decoder/vp9_onyxd.h
@@ -11,14 +11,14 @@
 #ifndef VP9_DECODER_VP9_ONYXD_H_
 #define VP9_DECODER_VP9_ONYXD_H_
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 #include "vpx_scale/yv12config.h"
 #include "vp9/common/vp9_ppflags.h"
 #include "vpx/vpx_codec.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef void *VP9D_PTR;
 
 typedef struct {
@@ -63,7 +63,7 @@ VP9D_PTR vp9_create_decompressor(VP9D_CONFIG *oxcf);
 void vp9_remove_decompressor(VP9D_PTR comp);
 
 #ifdef __cplusplus
-}
+}  // extern "C"
 #endif
 
 #endif  // VP9_DECODER_VP9_ONYXD_H_
diff --git a/vp9/decoder/vp9_onyxd_int.h b/vp9/decoder/vp9_onyxd_int.h
index e90f8923c..242c600cc 100644
--- a/vp9/decoder/vp9_onyxd_int.h
+++ b/vp9/decoder/vp9_onyxd_int.h
@@ -17,6 +17,10 @@
 #include "vp9/decoder/vp9_onyxd.h"
 #include "vp9/decoder/vp9_thread.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct VP9Decompressor {
   DECLARE_ALIGNED(16, MACROBLOCKD, mb);
 
@@ -53,4 +57,8 @@ typedef struct VP9Decompressor {
   PARTITION_CONTEXT *above_seg_context;
 } VP9D_COMP;
 
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
 #endif  // VP9_DECODER_VP9_ONYXD_INT_H_
diff --git a/vp9/decoder/vp9_read_bit_buffer.h b/vp9/decoder/vp9_read_bit_buffer.h
index 41a686837..619e39f1e 100644
--- a/vp9/decoder/vp9_read_bit_buffer.h
+++ b/vp9/decoder/vp9_read_bit_buffer.h
@@ -15,6 +15,10 @@
 
 #include "vpx/vpx_integer.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef void (*vp9_rb_error_handler)(void *data, size_t bit_offset);
 
 struct vp9_read_bit_buffer {
@@ -57,4 +61,8 @@ static int vp9_rb_read_signed_literal(struct vp9_read_bit_buffer *rb,
   return vp9_rb_read_bit(rb) ? -value : value;
 }
 
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
 #endif  // VP9_DECODER_VP9_READ_BIT_BUFFER_H_
diff --git a/vp9/decoder/vp9_reader.h b/vp9/decoder/vp9_reader.h
index 38cf0f621..8fe6acbc2 100644
--- a/vp9/decoder/vp9_reader.h
+++ b/vp9/decoder/vp9_reader.h
@@ -20,6 +20,10 @@
 
 #include "vp9/common/vp9_prob.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef size_t BD_VALUE;
 
 #define BD_VALUE_SIZE ((int)sizeof(BD_VALUE) * CHAR_BIT)
@@ -100,4 +104,8 @@ static int vp9_read_tree(vp9_reader *r, const vp9_tree_index *tree,
   return -i;
 }
 
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
 #endif  // VP9_DECODER_VP9_READER_H_
diff --git a/vp9/decoder/vp9_thread.h b/vp9/decoder/vp9_thread.h
index a624f3c2a..bc69cfa1f 100644
--- a/vp9/decoder/vp9_thread.h
+++ b/vp9/decoder/vp9_thread.h
@@ -19,7 +19,7 @@
 
 #include "./vpx_config.h"
 
-#if defined(__cplusplus) || defined(c_plusplus)
+#ifdef __cplusplus
 extern "C" {
 #endif
 
@@ -91,7 +91,7 @@ void vp9_worker_end(VP9Worker* const worker);
 
 //------------------------------------------------------------------------------
 
-#if defined(__cplusplus) || defined(c_plusplus)
+#ifdef __cplusplus
 }    // extern "C"
 #endif