diff --git a/src/cross.cu b/src/cross.cu
index f6683502b..62dee9461 100644
--- a/src/cross.cu
+++ b/src/cross.cu
@@ -11,7 +11,7 @@
 
 uint3 CpuBlock, CpuThread, CpuSize;
 
-void memcpy2D(void * dst_, int dpitch, void * src_, int spitch, int width, int height) {
+void memcpy2D(void * dst_, int dpitch, const void * src_, int spitch, int width, int height) {
 	char * dst = (char*) dst_, *src = (char*) src_;
 	for (int i=0; i<height; i++) {
 		memcpy(dst + i*dpitch, src + i*spitch, width);
diff --git a/src/cross.h b/src/cross.h
index 7349cc07d..895e66a67 100644
--- a/src/cross.h
+++ b/src/cross.h
@@ -306,7 +306,7 @@
       CPUKernelRun(func, blocks, std::forward<P>(args)...);
     }
 
-    void memcpy2D(void * dst_, int dpitch, void * src_, int spitch, int width, int height);
+    void memcpy2D(void * dst_, int dpitch, const void * src_, int spitch, int width, int height);
 
     template <class T, class P> inline T data_cast(const P& x) {
       static_assert(sizeof(T)==sizeof(P),"Wrong sizes in data_cast");