diff --git a/vpx_dsp/ssim.c b/vpx_dsp/ssim.c
index c795a9313..e69c8131b 100644
--- a/vpx_dsp/ssim.c
+++ b/vpx_dsp/ssim.c
@@ -13,7 +13,7 @@
 #include "vpx_dsp/ssim.h"
 #include "vpx_ports/mem.h"
 
-void vpx_ssim_parms_16x16_c(uint8_t *s, int sp, uint8_t *r,
+void vpx_ssim_parms_16x16_c(const uint8_t *s, int sp, const uint8_t *r,
                             int rp, uint32_t *sum_s, uint32_t *sum_r,
                             uint32_t *sum_sq_s, uint32_t *sum_sq_r,
                             uint32_t *sum_sxr) {
@@ -28,7 +28,7 @@ void vpx_ssim_parms_16x16_c(uint8_t *s, int sp, uint8_t *r,
     }
   }
 }
-void vpx_ssim_parms_8x8_c(uint8_t *s, int sp, uint8_t *r, int rp,
+void vpx_ssim_parms_8x8_c(const uint8_t *s, int sp, const uint8_t *r, int rp,
                           uint32_t *sum_s, uint32_t *sum_r,
                           uint32_t *sum_sq_s, uint32_t *sum_sq_r,
                           uint32_t *sum_sxr) {
@@ -45,7 +45,8 @@ void vpx_ssim_parms_8x8_c(uint8_t *s, int sp, uint8_t *r, int rp,
 }
 
 #if CONFIG_VP9_HIGHBITDEPTH
-void vpx_highbd_ssim_parms_8x8_c(uint16_t *s, int sp, uint16_t *r, int rp,
+void vpx_highbd_ssim_parms_8x8_c(const uint16_t *s, int sp,
+                                 const uint16_t *r, int rp,
                                  uint32_t *sum_s, uint32_t *sum_r,
                                  uint32_t *sum_sq_s, uint32_t *sum_sq_r,
                                  uint32_t *sum_sxr) {
@@ -85,7 +86,7 @@ static double similarity(uint32_t sum_s, uint32_t sum_r,
   return ssim_n * 1.0 / ssim_d;
 }
 
-static double ssim_8x8(uint8_t *s, int sp, uint8_t *r, int rp) {
+static double ssim_8x8(const uint8_t *s, int sp, const uint8_t *r, int rp) {
   uint32_t sum_s = 0, sum_r = 0, sum_sq_s = 0, sum_sq_r = 0, sum_sxr = 0;
   vpx_ssim_parms_8x8(s, sp, r, rp, &sum_s, &sum_r, &sum_sq_s, &sum_sq_r,
                      &sum_sxr);
@@ -93,8 +94,8 @@ static double ssim_8x8(uint8_t *s, int sp, uint8_t *r, int rp) {
 }
 
 #if CONFIG_VP9_HIGHBITDEPTH
-static double highbd_ssim_8x8(uint16_t *s, int sp, uint16_t *r, int rp,
-                              unsigned int bd) {
+static double highbd_ssim_8x8(const uint16_t *s, int sp, const uint16_t *r,
+                              int rp, unsigned int bd) {
   uint32_t sum_s = 0, sum_r = 0, sum_sq_s = 0, sum_sq_r = 0, sum_sxr = 0;
   const int oshift = bd - 8;
   vpx_highbd_ssim_parms_8x8(s, sp, r, rp, &sum_s, &sum_r, &sum_sq_s, &sum_sq_r,
@@ -111,8 +112,9 @@ static double highbd_ssim_8x8(uint16_t *s, int sp, uint16_t *r, int rp,
 // We are using a 8x8 moving window with starting location of each 8x8 window
 // on the 4x4 pixel grid. Such arrangement allows the windows to overlap
 // block boundaries to penalize blocking artifacts.
-double vpx_ssim2(uint8_t *img1, uint8_t *img2, int stride_img1,
-                 int stride_img2, int width, int height) {
+static double vpx_ssim2(const uint8_t *img1, const uint8_t *img2,
+                        int stride_img1, int stride_img2, int width,
+                        int height) {
   int i, j;
   int samples = 0;
   double ssim_total = 0;
@@ -131,9 +133,9 @@ double vpx_ssim2(uint8_t *img1, uint8_t *img2, int stride_img1,
 }
 
 #if CONFIG_VP9_HIGHBITDEPTH
-double vpx_highbd_ssim2(uint8_t *img1, uint8_t *img2, int stride_img1,
-                        int stride_img2, int width, int height,
-                        unsigned int bd) {
+static double vpx_highbd_ssim2(const uint8_t *img1, const uint8_t *img2,
+                               int stride_img1, int stride_img2, int width,
+                               int height, unsigned int bd) {
   int i, j;
   int samples = 0;
   double ssim_total = 0;
@@ -154,7 +156,8 @@ double vpx_highbd_ssim2(uint8_t *img1, uint8_t *img2, int stride_img1,
 }
 #endif  // CONFIG_VP9_HIGHBITDEPTH
 
-double vpx_calc_ssim(YV12_BUFFER_CONFIG *source, YV12_BUFFER_CONFIG *dest,
+double vpx_calc_ssim(const YV12_BUFFER_CONFIG *source,
+                     const YV12_BUFFER_CONFIG *dest,
                      double *weight) {
   double a, b, c;
   double ssimv;
@@ -178,7 +181,8 @@ double vpx_calc_ssim(YV12_BUFFER_CONFIG *source, YV12_BUFFER_CONFIG *dest,
   return ssimv;
 }
 
-double vpx_calc_ssimg(YV12_BUFFER_CONFIG *source, YV12_BUFFER_CONFIG *dest,
+double vpx_calc_ssimg(const YV12_BUFFER_CONFIG *source,
+                      const YV12_BUFFER_CONFIG *dest,
                       double *ssim_y, double *ssim_u, double *ssim_v) {
   double ssim_all = 0;
   double a, b, c;
@@ -231,7 +235,7 @@ double vpx_calc_ssimg(YV12_BUFFER_CONFIG *source, YV12_BUFFER_CONFIG *dest,
 // Replace c1 with n*n * c1 for the final step that leads to this code:
 // The final step scales by 12 bits so we don't lose precision in the constants.
 
-double ssimv_similarity(Ssimv *sv, int64_t n) {
+static double ssimv_similarity(const Ssimv *sv, int64_t n) {
   // Scale the constants by number of pixels.
   const int64_t c1 = (cc1 * n * n) >> 12;
   const int64_t c2 = (cc2 * n * n) >> 12;
@@ -262,7 +266,7 @@ double ssimv_similarity(Ssimv *sv, int64_t n) {
 //
 // 255 * 255 - (sum_s - sum_r) / count * (sum_s - sum_r) / count
 //
-double ssimv_similarity2(Ssimv *sv, int64_t n) {
+static double ssimv_similarity2(const Ssimv *sv, int64_t n) {
   // Scale the constants by number of pixels.
   const int64_t c1 = (cc1 * n * n) >> 12;
   const int64_t c2 = (cc2 * n * n) >> 12;
@@ -278,8 +282,8 @@ double ssimv_similarity2(Ssimv *sv, int64_t n) {
 
   return l * v;
 }
-void ssimv_parms(uint8_t *img1, int img1_pitch, uint8_t *img2, int img2_pitch,
-                 Ssimv *sv) {
+static void ssimv_parms(uint8_t *img1, int img1_pitch, uint8_t *img2,
+                        int img2_pitch, Ssimv *sv) {
   vpx_ssim_parms_8x8(img1, img1_pitch, img2, img2_pitch,
                      &sv->sum_s, &sv->sum_r, &sv->sum_sq_s, &sv->sum_sq_r,
                      &sv->sum_sxr);
@@ -448,8 +452,8 @@ double vpx_get_ssim_metrics(uint8_t *img1, int img1_pitch,
 
 
 #if CONFIG_VP9_HIGHBITDEPTH
-double vpx_highbd_calc_ssim(YV12_BUFFER_CONFIG *source,
-                            YV12_BUFFER_CONFIG *dest,
+double vpx_highbd_calc_ssim(const YV12_BUFFER_CONFIG *source,
+                            const YV12_BUFFER_CONFIG *dest,
                             double *weight, unsigned int bd) {
   double a, b, c;
   double ssimv;
@@ -473,8 +477,8 @@ double vpx_highbd_calc_ssim(YV12_BUFFER_CONFIG *source,
   return ssimv;
 }
 
-double vpx_highbd_calc_ssimg(YV12_BUFFER_CONFIG *source,
-                             YV12_BUFFER_CONFIG *dest, double *ssim_y,
+double vpx_highbd_calc_ssimg(const YV12_BUFFER_CONFIG *source,
+                             const YV12_BUFFER_CONFIG *dest, double *ssim_y,
                              double *ssim_u, double *ssim_v, unsigned int bd) {
   double ssim_all = 0;
   double a, b, c;
diff --git a/vpx_dsp/ssim.h b/vpx_dsp/ssim.h
index 47c48788f..d25e7145d 100644
--- a/vpx_dsp/ssim.h
+++ b/vpx_dsp/ssim.h
@@ -72,10 +72,12 @@ double vpx_get_ssim_metrics(uint8_t *img1, int img1_pitch, uint8_t *img2,
                       int img2_pitch, int width, int height, Ssimv *sv2,
                       Metrics *m, int do_inconsistency);
 
-double vpx_calc_ssim(YV12_BUFFER_CONFIG *source, YV12_BUFFER_CONFIG *dest,
+double vpx_calc_ssim(const YV12_BUFFER_CONFIG *source,
+                     const YV12_BUFFER_CONFIG *dest,
                      double *weight);
 
-double vpx_calc_ssimg(YV12_BUFFER_CONFIG *source, YV12_BUFFER_CONFIG *dest,
+double vpx_calc_ssimg(const YV12_BUFFER_CONFIG *source,
+                      const YV12_BUFFER_CONFIG *dest,
                       double *ssim_y, double *ssim_u, double *ssim_v);
 
 double vpx_calc_fastssim(YV12_BUFFER_CONFIG *source, YV12_BUFFER_CONFIG *dest,
@@ -86,13 +88,13 @@ double vpx_psnrhvs(const YV12_BUFFER_CONFIG *source,
                    double *ssim_y, double *ssim_u, double *ssim_v);
 
 #if CONFIG_VP9_HIGHBITDEPTH
-double vpx_highbd_calc_ssim(YV12_BUFFER_CONFIG *source,
-                            YV12_BUFFER_CONFIG *dest,
+double vpx_highbd_calc_ssim(const YV12_BUFFER_CONFIG *source,
+                            const YV12_BUFFER_CONFIG *dest,
                             double *weight,
                             unsigned int bd);
 
-double vpx_highbd_calc_ssimg(YV12_BUFFER_CONFIG *source,
-                             YV12_BUFFER_CONFIG *dest,
+double vpx_highbd_calc_ssimg(const YV12_BUFFER_CONFIG *source,
+                             const YV12_BUFFER_CONFIG *dest,
                              double *ssim_y,
                              double *ssim_u,
                              double *ssim_v,
diff --git a/vpx_dsp/vpx_dsp_rtcd_defs.pl b/vpx_dsp/vpx_dsp_rtcd_defs.pl
index f1a366c3f..6c8420e8b 100644
--- a/vpx_dsp/vpx_dsp_rtcd_defs.pl
+++ b/vpx_dsp/vpx_dsp_rtcd_defs.pl
@@ -994,10 +994,10 @@ specialize qw/vpx_sad4x4x4d msa/, "$sse_x86inc";
 # Structured Similarity (SSIM)
 #
 if (vpx_config("CONFIG_INTERNAL_STATS") eq "yes") {
-    add_proto qw/void vpx_ssim_parms_8x8/, "uint8_t *s, int sp, uint8_t *r, int rp, uint32_t *sum_s, uint32_t *sum_r, uint32_t *sum_sq_s, uint32_t *sum_sq_r, uint32_t *sum_sxr";
+    add_proto qw/void vpx_ssim_parms_8x8/, "const uint8_t *s, int sp, const uint8_t *r, int rp, uint32_t *sum_s, uint32_t *sum_r, uint32_t *sum_sq_s, uint32_t *sum_sq_r, uint32_t *sum_sxr";
     specialize qw/vpx_ssim_parms_8x8/, "$sse2_x86_64";
 
-    add_proto qw/void vpx_ssim_parms_16x16/, "uint8_t *s, int sp, uint8_t *r, int rp, uint32_t *sum_s, uint32_t *sum_r, uint32_t *sum_sq_s, uint32_t *sum_sq_r, uint32_t *sum_sxr";
+    add_proto qw/void vpx_ssim_parms_16x16/, "const uint8_t *s, int sp, const uint8_t *r, int rp, uint32_t *sum_s, uint32_t *sum_r, uint32_t *sum_sq_s, uint32_t *sum_sq_r, uint32_t *sum_sxr";
     specialize qw/vpx_ssim_parms_16x16/, "$sse2_x86_64";
 }