diff --git a/src/glu/sgi/libnurbs/interface/insurfeval.cc b/src/glu/sgi/libnurbs/interface/insurfeval.cc
index b314699c7af..e4ee3ef6a29 100644
--- a/src/glu/sgi/libnurbs/interface/insurfeval.cc
+++ b/src/glu/sgi/libnurbs/interface/insurfeval.cc
@@ -1533,8 +1533,8 @@ void OpenGLSurfaceEvaluator::inEvalVStrip(int n_left, REAL u_left, REAL* left_va
     }
   //clean up 
   free(leftXYZ);
-  free(leftXYZ);
-  free(rightNormal);
+  free(rightXYZ);
+  free(leftNormal);
   free(rightNormal);
 }