diff --git a/rtengine/rawimagesource.cc b/rtengine/rawimagesource.cc
index b6444dd83..9da266610 100644
--- a/rtengine/rawimagesource.cc
+++ b/rtengine/rawimagesource.cc
@@ -3042,10 +3042,17 @@ void RawImageSource::copyOriginalPixels(const RAWParams &raw, RawImage *src, Raw
 
 SSEFUNCTION void RawImageSource::cfaboxblur(RawImage *riFlatFile, float* cfablur, const int boxH, const int boxW)
 {
+
+    if(boxW == 0 && boxH == 0) { // nothing to blur
+        memcpy(cfablur, riFlatFile->data[0], W*H*sizeof(float));
+        return;
+    }
+
     float *tmpBuffer = nullptr;
     float *cfatmp = nullptr;
     float *srcVertical = nullptr;
 
+
     if(boxH > 0 && boxW > 0) {
         // we need a temporary buffer if we have to blur both directions
         tmpBuffer = (float (*)) calloc (H * W, sizeof * tmpBuffer);
@@ -3065,7 +3072,6 @@ SSEFUNCTION void RawImageSource::cfaboxblur(RawImage *riFlatFile, float* cfablur
         srcVertical = cfatmp;
     }
 
-
 #ifdef _OPENMP
     #pragma omp parallel
 #endif