diff --git a/rtengine/rtthumbnail.cc b/rtengine/rtthumbnail.cc
index 671fd6f96..d636c718d 100644
--- a/rtengine/rtthumbnail.cc
+++ b/rtengine/rtthumbnail.cc
@@ -767,6 +767,7 @@ IImage8* Thumbnail::processImage (const procparams::ProcParams& params, int rhei
 }
 
 int Thumbnail::getImageWidth (const procparams::ProcParams& params, int rheight) {
+	if (thumbImg==NULL) return 0;  // Can happen if thumb is just building and GUI comes in with resize wishes
 
     int rwidth;
     if (params.coarse.rotate==90 || params.coarse.rotate==270) 
@@ -878,6 +879,7 @@ void Thumbnail::getSpotWB (const procparams::ProcParams& params, int xp, int yp,
     rtemp = ct.getTemp ();
     rgreen = ct.getGreen ();
 }
+
 void Thumbnail::transformPixel (int x, int y, int tran, int& tx, int& ty) {
     
     int W = thumbImg->width;
diff --git a/rtgui/thumbnail.cc b/rtgui/thumbnail.cc
index a24351431..153130109 100644
--- a/rtgui/thumbnail.cc
+++ b/rtgui/thumbnail.cc
@@ -272,11 +272,9 @@ void Thumbnail::decreaseRef ()
 }
 
 void Thumbnail::getThumbnailSize (int &w, int &h) {
-
-    if (tpp) 
-        w = tpp->getImageWidth (getProcParams(), h);
-    else
-        w = tw * h / th;
+	w=0;
+	if (tpp) w = tpp->getImageWidth (getProcParams(), h);  // this might return 0 if image was just building
+    if (w==0) w = tw * h / th;
 }
 
 rtengine::IImage8* Thumbnail::processThumbImage (const rtengine::procparams::ProcParams& pparams, int h, double& scale) {