diff --git a/celt/bands.c b/celt/bands.c
index b88513ab..f38b6626 100644
--- a/celt/bands.c
+++ b/celt/bands.c
@@ -111,7 +111,7 @@ void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *band
 }
 
 /* Normalise each band such that the energy is one. */
-void normalise_bands(const CELTMode *m, const celt_sig * restrict freq, celt_norm * restrict X, const celt_ener *bandE, int end, int C, int M)
+void normalise_bands(const CELTMode *m, const celt_sig * OPUS_RESTRICT freq, celt_norm * OPUS_RESTRICT X, const celt_ener *bandE, int end, int C, int M)
 {
    int i, c, N;
    const opus_int16 *eBands = m->eBands;
@@ -153,7 +153,7 @@ void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *band
 }
 
 /* Normalise each band such that the energy is one. */
-void normalise_bands(const CELTMode *m, const celt_sig * restrict freq, celt_norm * restrict X, const celt_ener *bandE, int end, int C, int M)
+void normalise_bands(const CELTMode *m, const celt_sig * OPUS_RESTRICT freq, celt_norm * OPUS_RESTRICT X, const celt_ener *bandE, int end, int C, int M)
 {
    int i, c, N;
    const opus_int16 *eBands = m->eBands;
@@ -172,15 +172,15 @@ void normalise_bands(const CELTMode *m, const celt_sig * restrict freq, celt_nor
 #endif /* FIXED_POINT */
 
 /* De-normalise the energy to produce the synthesis from the unit-energy bands */
-void denormalise_bands(const CELTMode *m, const celt_norm * restrict X, celt_sig * restrict freq, const celt_ener *bandE, int end, int C, int M)
+void denormalise_bands(const CELTMode *m, const celt_norm * OPUS_RESTRICT X, celt_sig * OPUS_RESTRICT freq, const celt_ener *bandE, int end, int C, int M)
 {
    int i, c, N;
    const opus_int16 *eBands = m->eBands;
    N = M*m->shortMdctSize;
    celt_assert2(C<=2, "denormalise_bands() not implemented for >2 channels");
    c=0; do {
-      celt_sig * restrict f;
-      const celt_norm * restrict x;
+      celt_sig * OPUS_RESTRICT f;
+      const celt_norm * OPUS_RESTRICT x;
       f = freq+c*N;
       x = X+c*N;
       for (i=0;i<end;i++)
@@ -397,7 +397,7 @@ int spreading_decision(const CELTMode *m, celt_norm *X, int *average,
 {
    int i, c, N0;
    int sum = 0, nbBands=0;
-   const opus_int16 * restrict eBands = m->eBands;
+   const opus_int16 * OPUS_RESTRICT eBands = m->eBands;
    int decision;
    int hf_sum=0;
 
@@ -412,7 +412,7 @@ int spreading_decision(const CELTMode *m, celt_norm *X, int *average,
       {
          int j, N, tmp=0;
          int tcount[3] = {0,0,0};
-         celt_norm * restrict x = X+M*eBands[i]+c*N0;
+         celt_norm * OPUS_RESTRICT x = X+M*eBands[i]+c*N0;
          N = M*(eBands[i+1]-eBands[i]);
          if (N<=8)
             continue;
@@ -1175,8 +1175,8 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
 {
    int i;
    opus_int32 remaining_bits;
-   const opus_int16 * restrict eBands = m->eBands;
-   celt_norm * restrict norm, * restrict norm2;
+   const opus_int16 * OPUS_RESTRICT eBands = m->eBands;
+   celt_norm * OPUS_RESTRICT norm, * OPUS_RESTRICT norm2;
    VARDECL(celt_norm, _norm);
    VARDECL(celt_norm, lowband_scratch);
    int B;
@@ -1206,7 +1206,7 @@ void quant_all_bands(int encode, const CELTMode *m, int start, int end,
       int N;
       opus_int32 curr_balance;
       int effective_lowband=-1;
-      celt_norm * restrict X, * restrict Y;
+      celt_norm * OPUS_RESTRICT X, * OPUS_RESTRICT Y;
       int tf_change=0;
       unsigned x_cm;
       unsigned y_cm;
diff --git a/celt/bands.h b/celt/bands.h
index cce16a09..9ff8ffd7 100644
--- a/celt/bands.h
+++ b/celt/bands.h
@@ -51,14 +51,14 @@ void compute_band_energies(const CELTMode *m, const celt_sig *X, celt_ener *band
  * @param X Spectrum (returned normalised)
  * @param bands Square root of the energy for each band
  */
-void normalise_bands(const CELTMode *m, const celt_sig * restrict freq, celt_norm * restrict X, const celt_ener *bandE, int end, int C, int M);
+void normalise_bands(const CELTMode *m, const celt_sig * OPUS_RESTRICT freq, celt_norm * OPUS_RESTRICT X, const celt_ener *bandE, int end, int C, int M);
 
 /** Denormalise each band of X to restore full amplitude
  * @param m Mode data
  * @param X Spectrum (returned de-normalised)
  * @param bands Square root of the energy for each band
  */
-void denormalise_bands(const CELTMode *m, const celt_norm * restrict X, celt_sig * restrict freq, const celt_ener *bandE, int end, int C, int M);
+void denormalise_bands(const CELTMode *m, const celt_norm * OPUS_RESTRICT X, celt_sig * OPUS_RESTRICT freq, const celt_ener *bandE, int end, int C, int M);
 
 #define SPREAD_NONE       (0)
 #define SPREAD_LIGHT      (1)
diff --git a/celt/celt.c b/celt/celt.c
index cfdfaafe..4f16887d 100644
--- a/celt/celt.c
+++ b/celt/celt.c
@@ -291,7 +291,7 @@ static inline opus_val16 SIG2WORD16(celt_sig x)
 #endif
 }
 
-static int transient_analysis(const opus_val32 * restrict in, int len, int C,
+static int transient_analysis(const opus_val32 * OPUS_RESTRICT in, int len, int C,
                               int overlap)
 {
    int i;
@@ -383,7 +383,7 @@ static int transient_analysis(const opus_val32 * restrict in, int len, int C,
 
 /** Apply window and compute the MDCT for all sub-frames and
     all channels in a frame */
-static void compute_mdcts(const CELTMode *mode, int shortBlocks, celt_sig * restrict in, celt_sig * restrict out, int C, int LM)
+static void compute_mdcts(const CELTMode *mode, int shortBlocks, celt_sig * OPUS_RESTRICT in, celt_sig * OPUS_RESTRICT out, int C, int LM)
 {
    if (C==1 && !shortBlocks)
    {
@@ -412,8 +412,8 @@ static void compute_mdcts(const CELTMode *mode, int shortBlocks, celt_sig * rest
 /** Compute the IMDCT and apply window for all sub-frames and
     all channels in a frame */
 static void compute_inv_mdcts(const CELTMode *mode, int shortBlocks, celt_sig *X,
-      celt_sig * restrict out_mem[],
-      celt_sig * restrict overlap_mem[], int C, int LM)
+      celt_sig * OPUS_RESTRICT out_mem[],
+      celt_sig * OPUS_RESTRICT overlap_mem[], int C, int LM)
 {
    int c;
    const int N = mode->shortMdctSize<<LM;
@@ -458,8 +458,8 @@ static void deemphasis(celt_sig *in[], opus_val16 *pcm, int N, int C, int downsa
    int count=0;
    c=0; do {
       int j;
-      celt_sig * restrict x;
-      opus_val16  * restrict y;
+      celt_sig * OPUS_RESTRICT x;
+      opus_val16  * OPUS_RESTRICT y;
       celt_sig m = mem[c];
       x =in[c];
       y = pcm+c;
@@ -879,7 +879,7 @@ static int stereo_analysis(const CELTMode *m, const celt_norm *X,
          > MULT16_32_Q15(m->eBands[13]<<(LM+1), sumLR);
 }
 
-int celt_encode_with_ec(CELTEncoder * restrict st, const opus_val16 * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes, ec_enc *enc)
+int celt_encode_with_ec(CELTEncoder * OPUS_RESTRICT st, const opus_val16 * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes, ec_enc *enc)
 {
    int i, c, N;
    opus_int32 bits;
@@ -1056,8 +1056,8 @@ int celt_encode_with_ec(CELTEncoder * restrict st, const opus_val16 * pcm, int f
       silence = 1;
       c=0; do {
          int count = 0;
-         const opus_val16 * restrict pcmp = pcm+c;
-         celt_sig * restrict inp = in+c*(N+st->overlap)+st->overlap;
+         const opus_val16 * OPUS_RESTRICT pcmp = pcm+c;
+         celt_sig * OPUS_RESTRICT inp = in+c*(N+st->overlap)+st->overlap;
 
          for (i=0;i<N;i++)
          {
@@ -1679,13 +1679,13 @@ int celt_encode_with_ec(CELTEncoder * restrict st, const opus_val16 * pcm, int f
 #ifdef CUSTOM_MODES
 
 #ifdef FIXED_POINT
-int opus_custom_encode(CELTEncoder * restrict st, const opus_int16 * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes)
+int opus_custom_encode(CELTEncoder * OPUS_RESTRICT st, const opus_int16 * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes)
 {
    return celt_encode_with_ec(st, pcm, frame_size, compressed, nbCompressedBytes, NULL);
 }
 
 #ifndef DISABLE_FLOAT_API
-int opus_custom_encode_float(CELTEncoder * restrict st, const float * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes)
+int opus_custom_encode_float(CELTEncoder * OPUS_RESTRICT st, const float * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes)
 {
    int j, ret, C, N;
    VARDECL(opus_int16, in);
@@ -1712,7 +1712,7 @@ int opus_custom_encode_float(CELTEncoder * restrict st, const float * pcm, int f
 #endif /* DISABLE_FLOAT_API */
 #else
 
-int opus_custom_encode(CELTEncoder * restrict st, const opus_int16 * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes)
+int opus_custom_encode(CELTEncoder * OPUS_RESTRICT st, const opus_int16 * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes)
 {
    int j, ret, C, N;
    VARDECL(celt_sig, in);
@@ -1737,7 +1737,7 @@ int opus_custom_encode(CELTEncoder * restrict st, const opus_int16 * pcm, int fr
    return ret;
 }
 
-int opus_custom_encode_float(CELTEncoder * restrict st, const float * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes)
+int opus_custom_encode_float(CELTEncoder * OPUS_RESTRICT st, const float * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes)
 {
    return celt_encode_with_ec(st, pcm, frame_size, compressed, nbCompressedBytes, NULL);
 }
@@ -1746,7 +1746,7 @@ int opus_custom_encode_float(CELTEncoder * restrict st, const float * pcm, int f
 
 #endif /* CUSTOM_MODES */
 
-int opus_custom_encoder_ctl(CELTEncoder * restrict st, int request, ...)
+int opus_custom_encoder_ctl(CELTEncoder * OPUS_RESTRICT st, int request, ...)
 {
    va_list ap;
 
@@ -2008,7 +2008,7 @@ void opus_custom_decoder_destroy(CELTDecoder *st)
 }
 #endif /* CUSTOM_MODES */
 
-static void celt_decode_lost(CELTDecoder * restrict st, opus_val16 * restrict pcm, int N, int LM)
+static void celt_decode_lost(CELTDecoder * OPUS_RESTRICT st, opus_val16 * OPUS_RESTRICT pcm, int N, int LM)
 {
    int c;
    int pitch_index;
@@ -2269,7 +2269,7 @@ static void celt_decode_lost(CELTDecoder * restrict st, opus_val16 * restrict pc
    RESTORE_STACK;
 }
 
-int celt_decode_with_ec(CELTDecoder * restrict st, const unsigned char *data, int len, opus_val16 * restrict pcm, int frame_size, ec_dec *dec)
+int celt_decode_with_ec(CELTDecoder * OPUS_RESTRICT st, const unsigned char *data, int len, opus_val16 * OPUS_RESTRICT pcm, int frame_size, ec_dec *dec)
 {
    int c, i, N;
    int spread_decision;
@@ -2651,13 +2651,13 @@ int celt_decode_with_ec(CELTDecoder * restrict st, const unsigned char *data, in
 #ifdef CUSTOM_MODES
 
 #ifdef FIXED_POINT
-int opus_custom_decode(CELTDecoder * restrict st, const unsigned char *data, int len, opus_int16 * restrict pcm, int frame_size)
+int opus_custom_decode(CELTDecoder * OPUS_RESTRICT st, const unsigned char *data, int len, opus_int16 * OPUS_RESTRICT pcm, int frame_size)
 {
    return celt_decode_with_ec(st, data, len, pcm, frame_size, NULL);
 }
 
 #ifndef DISABLE_FLOAT_API
-int opus_custom_decode_float(CELTDecoder * restrict st, const unsigned char *data, int len, float * restrict pcm, int frame_size)
+int opus_custom_decode_float(CELTDecoder * OPUS_RESTRICT st, const unsigned char *data, int len, float * OPUS_RESTRICT pcm, int frame_size)
 {
    int j, ret, C, N;
    VARDECL(opus_int16, out);
@@ -2682,12 +2682,12 @@ int opus_custom_decode_float(CELTDecoder * restrict st, const unsigned char *dat
 
 #else
 
-int opus_custom_decode_float(CELTDecoder * restrict st, const unsigned char *data, int len, float * restrict pcm, int frame_size)
+int opus_custom_decode_float(CELTDecoder * OPUS_RESTRICT st, const unsigned char *data, int len, float * OPUS_RESTRICT pcm, int frame_size)
 {
    return celt_decode_with_ec(st, data, len, pcm, frame_size, NULL);
 }
 
-int opus_custom_decode(CELTDecoder * restrict st, const unsigned char *data, int len, opus_int16 * restrict pcm, int frame_size)
+int opus_custom_decode(CELTDecoder * OPUS_RESTRICT st, const unsigned char *data, int len, opus_int16 * OPUS_RESTRICT pcm, int frame_size)
 {
    int j, ret, C, N;
    VARDECL(celt_sig, out);
@@ -2713,7 +2713,7 @@ int opus_custom_decode(CELTDecoder * restrict st, const unsigned char *data, int
 #endif
 #endif /* CUSTOM_MODES */
 
-int opus_custom_decoder_ctl(CELTDecoder * restrict st, int request, ...)
+int opus_custom_decoder_ctl(CELTDecoder * OPUS_RESTRICT st, int request, ...)
 {
    va_list ap;
 
diff --git a/celt/celt.h b/celt/celt.h
index da4464ce..218cd883 100644
--- a/celt/celt.h
+++ b/celt/celt.h
@@ -92,7 +92,7 @@ extern "C" {
 
 int celt_encoder_get_size(int channels);
 
-int celt_encode_with_ec(OpusCustomEncoder * restrict st, const opus_val16 * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes, ec_enc *enc);
+int celt_encode_with_ec(OpusCustomEncoder * OPUS_RESTRICT st, const opus_val16 * pcm, int frame_size, unsigned char *compressed, int nbCompressedBytes, ec_enc *enc);
 
 int celt_encoder_init(CELTEncoder *st, opus_int32 sampling_rate, int channels);
 
@@ -105,7 +105,7 @@ int celt_decoder_get_size(int channels);
 
 int celt_decoder_init(CELTDecoder *st, opus_int32 sampling_rate, int channels);
 
-int celt_decode_with_ec(OpusCustomDecoder * restrict st, const unsigned char *data, int len, opus_val16 * restrict pcm, int frame_size, ec_dec *dec);
+int celt_decode_with_ec(OpusCustomDecoder * OPUS_RESTRICT st, const unsigned char *data, int len, opus_val16 * OPUS_RESTRICT pcm, int frame_size, ec_dec *dec);
 
 #define celt_encoder_ctl opus_custom_encoder_ctl
 #define celt_decoder_ctl opus_custom_decoder_ctl
diff --git a/celt/mdct.c b/celt/mdct.c
index 3193b7cc..16a36c69 100644
--- a/celt/mdct.c
+++ b/celt/mdct.c
@@ -102,7 +102,7 @@ void clt_mdct_clear(mdct_lookup *l)
 #endif /* CUSTOM_MODES */
 
 /* Forward MDCT trashes the input array */
-void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * restrict out,
+void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * OPUS_RESTRICT out,
       const opus_val16 *window, int overlap, int shift, int stride)
 {
    int i;
@@ -126,11 +126,11 @@ void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar
    /* Window, shuffle, fold */
    {
       /* Temp pointers to make it really clear to the compiler what we're doing */
-      const kiss_fft_scalar * restrict xp1 = in+(overlap>>1);
-      const kiss_fft_scalar * restrict xp2 = in+N2-1+(overlap>>1);
-      kiss_fft_scalar * restrict yp = f;
-      const opus_val16 * restrict wp1 = window+(overlap>>1);
-      const opus_val16 * restrict wp2 = window+(overlap>>1)-1;
+      const kiss_fft_scalar * OPUS_RESTRICT xp1 = in+(overlap>>1);
+      const kiss_fft_scalar * OPUS_RESTRICT xp2 = in+N2-1+(overlap>>1);
+      kiss_fft_scalar * OPUS_RESTRICT yp = f;
+      const opus_val16 * OPUS_RESTRICT wp1 = window+(overlap>>1);
+      const opus_val16 * OPUS_RESTRICT wp2 = window+(overlap>>1)-1;
       for(i=0;i<(overlap>>2);i++)
       {
          /* Real part arranged as -d-cR, Imag part arranged as -b+aR*/
@@ -164,7 +164,7 @@ void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar
    }
    /* Pre-rotation */
    {
-      kiss_fft_scalar * restrict yp = f;
+      kiss_fft_scalar * OPUS_RESTRICT yp = f;
       const kiss_twiddle_scalar *t = &l->trig[0];
       for(i=0;i<N4;i++)
       {
@@ -185,9 +185,9 @@ void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar
    /* Post-rotate */
    {
       /* Temp pointers to make it really clear to the compiler what we're doing */
-      const kiss_fft_scalar * restrict fp = in;
-      kiss_fft_scalar * restrict yp1 = out;
-      kiss_fft_scalar * restrict yp2 = out+stride*(N2-1);
+      const kiss_fft_scalar * OPUS_RESTRICT fp = in;
+      kiss_fft_scalar * OPUS_RESTRICT yp1 = out;
+      kiss_fft_scalar * OPUS_RESTRICT yp2 = out+stride*(N2-1);
       const kiss_twiddle_scalar *t = &l->trig[0];
       /* Temp pointers to make it really clear to the compiler what we're doing */
       for(i=0;i<N4;i++)
@@ -206,8 +206,8 @@ void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar
    RESTORE_STACK;
 }
 
-void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * restrict out,
-      const opus_val16 * restrict window, int overlap, int shift, int stride)
+void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * OPUS_RESTRICT out,
+      const opus_val16 * OPUS_RESTRICT window, int overlap, int shift, int stride)
 {
    int i;
    int N, N2, N4;
@@ -231,9 +231,9 @@ void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scala
    /* Pre-rotate */
    {
       /* Temp pointers to make it really clear to the compiler what we're doing */
-      const kiss_fft_scalar * restrict xp1 = in;
-      const kiss_fft_scalar * restrict xp2 = in+stride*(N2-1);
-      kiss_fft_scalar * restrict yp = f2;
+      const kiss_fft_scalar * OPUS_RESTRICT xp1 = in;
+      const kiss_fft_scalar * OPUS_RESTRICT xp2 = in+stride*(N2-1);
+      kiss_fft_scalar * OPUS_RESTRICT yp = f2;
       const kiss_twiddle_scalar *t = &l->trig[0];
       for(i=0;i<N4;i++)
       {
@@ -253,7 +253,7 @@ void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scala
 
    /* Post-rotate */
    {
-      kiss_fft_scalar * restrict fp = f;
+      kiss_fft_scalar * OPUS_RESTRICT fp = f;
       const kiss_twiddle_scalar *t = &l->trig[0];
 
       for(i=0;i<N4;i++)
@@ -271,9 +271,9 @@ void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scala
    }
    /* De-shuffle the components for the middle of the window only */
    {
-      const kiss_fft_scalar * restrict fp1 = f;
-      const kiss_fft_scalar * restrict fp2 = f+N2-1;
-      kiss_fft_scalar * restrict yp = f2;
+      const kiss_fft_scalar * OPUS_RESTRICT fp1 = f;
+      const kiss_fft_scalar * OPUS_RESTRICT fp2 = f+N2-1;
+      kiss_fft_scalar * OPUS_RESTRICT yp = f2;
       for(i = 0; i < N4; i++)
       {
          *yp++ =-*fp1;
@@ -285,11 +285,11 @@ void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scala
    out -= (N2-overlap)>>1;
    /* Mirror on both sides for TDAC */
    {
-      kiss_fft_scalar * restrict fp1 = f2+N4-1;
-      kiss_fft_scalar * restrict xp1 = out+N2-1;
-      kiss_fft_scalar * restrict yp1 = out+N4-overlap/2;
-      const opus_val16 * restrict wp1 = window;
-      const opus_val16 * restrict wp2 = window+overlap-1;
+      kiss_fft_scalar * OPUS_RESTRICT fp1 = f2+N4-1;
+      kiss_fft_scalar * OPUS_RESTRICT xp1 = out+N2-1;
+      kiss_fft_scalar * OPUS_RESTRICT yp1 = out+N4-overlap/2;
+      const opus_val16 * OPUS_RESTRICT wp1 = window;
+      const opus_val16 * OPUS_RESTRICT wp2 = window+overlap-1;
       for(i = 0; i< N4-overlap/2; i++)
       {
          *xp1 = *fp1;
@@ -307,11 +307,11 @@ void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scala
       }
    }
    {
-      kiss_fft_scalar * restrict fp2 = f2+N4;
-      kiss_fft_scalar * restrict xp2 = out+N2;
-      kiss_fft_scalar * restrict yp2 = out+N-1-(N4-overlap/2);
-      const opus_val16 * restrict wp1 = window;
-      const opus_val16 * restrict wp2 = window+overlap-1;
+      kiss_fft_scalar * OPUS_RESTRICT fp2 = f2+N4;
+      kiss_fft_scalar * OPUS_RESTRICT xp2 = out+N2;
+      kiss_fft_scalar * OPUS_RESTRICT yp2 = out+N-1-(N4-overlap/2);
+      const opus_val16 * OPUS_RESTRICT wp1 = window;
+      const opus_val16 * OPUS_RESTRICT wp2 = window+overlap-1;
       for(i = 0; i< N4-overlap/2; i++)
       {
          *xp2 = *fp2;
diff --git a/celt/mdct.h b/celt/mdct.h
index 5ec26d0a..201f28b4 100644
--- a/celt/mdct.h
+++ b/celt/mdct.h
@@ -42,6 +42,7 @@
 #ifndef MDCT_H
 #define MDCT_H
 
+#include "opus_defines.h"
 #include "kiss_fft.h"
 #include "arch.h"
 
@@ -49,7 +50,7 @@ typedef struct {
    int n;
    int maxshift;
    const kiss_fft_state *kfft[4];
-   const kiss_twiddle_scalar * restrict trig;
+   const kiss_twiddle_scalar * OPUS_RESTRICT trig;
 } mdct_lookup;
 
 int clt_mdct_init(mdct_lookup *l,int N, int maxshift);
@@ -62,6 +63,6 @@ void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar
 /** Compute a backward MDCT (no scaling) and performs weighted overlap-add
     (scales implicitly by 1/2) */
 void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *out,
-      const opus_val16 * restrict window, int overlap, int shift, int stride);
+      const opus_val16 * OPUS_RESTRICT window, int overlap, int shift, int stride);
 
 #endif
diff --git a/celt/pitch.c b/celt/pitch.c
index 8e906878..c2f08ec1 100644
--- a/celt/pitch.c
+++ b/celt/pitch.c
@@ -102,7 +102,7 @@ static void find_best_pitch(opus_val32 *xcorr, opus_val16 *y, int len,
    }
 }
 
-void pitch_downsample(celt_sig * restrict x[], opus_val16 * restrict x_lp,
+void pitch_downsample(celt_sig * OPUS_RESTRICT x[], opus_val16 * OPUS_RESTRICT x_lp,
       int len, int C)
 {
    int i;
@@ -169,7 +169,7 @@ void pitch_downsample(celt_sig * restrict x[], opus_val16 * restrict x_lp,
 
 }
 
-void pitch_search(const opus_val16 * restrict x_lp, opus_val16 * restrict y,
+void pitch_search(const opus_val16 * OPUS_RESTRICT x_lp, opus_val16 * OPUS_RESTRICT y,
                   int len, int max_pitch, int *pitch)
 {
    int i, j;
diff --git a/celt/pitch.h b/celt/pitch.h
index 2509d64b..2757071a 100644
--- a/celt/pitch.h
+++ b/celt/pitch.h
@@ -36,10 +36,10 @@
 
 #include "modes.h"
 
-void pitch_downsample(celt_sig * restrict x[], opus_val16 * restrict x_lp,
+void pitch_downsample(celt_sig * OPUS_RESTRICT x[], opus_val16 * OPUS_RESTRICT x_lp,
       int len, int C);
 
-void pitch_search(const opus_val16 * restrict x_lp, opus_val16 * restrict y,
+void pitch_search(const opus_val16 * OPUS_RESTRICT x_lp, opus_val16 * OPUS_RESTRICT y,
                   int len, int max_pitch, int *pitch);
 
 opus_val16 remove_doubling(opus_val16 *x, int maxperiod, int minperiod,
diff --git a/celt/vq.c b/celt/vq.c
index a2a4fd36..98a0f36c 100644
--- a/celt/vq.c
+++ b/celt/vq.c
@@ -109,7 +109,7 @@ static void exp_rotation(celt_norm *X, int len, int dir, int stride, int K, int
 
 /** Takes the pitch vector and the decoded residual vector, computes the gain
     that will give ||p+g*y||=1 and mixes the residual with the pitch. */
-static void normalise_residual(int * restrict iy, celt_norm * restrict X,
+static void normalise_residual(int * OPUS_RESTRICT iy, celt_norm * OPUS_RESTRICT X,
       int N, opus_val32 Ryy, opus_val16 gain)
 {
    int i;
diff --git a/include/opus_defines.h b/include/opus_defines.h
index aad47fc4..a16bd648 100644
--- a/include/opus_defines.h
+++ b/include/opus_defines.h
@@ -84,6 +84,18 @@ extern "C" {
 #  endif
 # endif
 
+#if (!defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L) )
+# if OPUS_GNUC_PREREQ(3,0)
+#  define OPUS_RESTRICT __restrict__
+# elif (_MSC_VER >= 1400)
+#  define OPUS_RESTRICT __restrict
+# else
+#  define OPUS_RESTRICT
+# endif
+#else
+# define OPUS_RESTRICT restrict
+#endif
+
 /**Warning attributes for opus functions
   * NONNULL is not used in OPUS_BUILD to avoid the compiler optimizing out
   * some paranoid null checks. */