diff --git a/src/render.c b/src/render.c
index 4894642..be94f79 100644
--- a/src/render.c
+++ b/src/render.c
@@ -92,7 +92,7 @@ int pixel_render(const System *system, int i, int j, const Spline_data spline_da
   return MC_pixel_render(system, i, j, spline_data, rgb, pixel_render_max, pixel_render_err, r);
 }
 
-int render(System *system, double **buffer, int pixel_render_max, double pixel_render_err, double chi_rela_err) {
+int render(System *system, double *buffer[3], int pixel_render_max, double pixel_render_err, double chi_rela_err) {
   double h = (system->H)*(system->w)/(system->W);
   double tanpsi2 = (system->w)*(system->w)+h*h;
   double cotpsi2 = 1/tanpsi2;
diff --git a/src/render.h b/src/render.h
index c801d9f..708643f 100644
--- a/src/render.h
+++ b/src/render.h
@@ -1,4 +1,4 @@
 #include "common.h"
 #include "init.h"
 
-int render(System *system, double **buffer, int pixel_render_max, double pixel_render_err, double chi_rela_err);
+int render(System *system, double *buffer[3], int pixel_render_max, double pixel_render_err, double chi_rela_err);
diff --git a/src/write_png.c b/src/write_png.c
index a7b86ad..ffc74db 100644
--- a/src/write_png.c
+++ b/src/write_png.c
@@ -10,7 +10,7 @@ static inline double linear_to_srgb(double x){
   return 1.055 * pow(x, 1.0/2.4) - 0.055;
 }
 
-int buffer_normalize_srgb(double **buffer, int W, int H) {
+int buffer_normalize_srgb(double *buffer[3], int W, int H) {
   double max = 0;
   for (int j = 0; j < H; j++) {
     for (int i = 0; i < W; i++) {
@@ -31,7 +31,7 @@ int buffer_normalize_srgb(double **buffer, int W, int H) {
   return 0;
 }
 
-int write_png(char *filename, double **buffer, int W, int H) {
+int write_png(char *filename, double *buffer[3], int W, int H) {
   buffer_normalize_srgb(buffer, W, H);
   size_t bufsize = W*H*3;
   uint8_t *img = (uint8_t *)malloc(bufsize);
diff --git a/src/write_png.h b/src/write_png.h
index f849eb7..c83d893 100644
--- a/src/write_png.h
+++ b/src/write_png.h
@@ -1,3 +1,3 @@
 
 
-int write_png(char *filename, double **buffer, int W, int H);
+int write_png(char *filename, double *buffer[3], int W, int H);