diff --git a/src/avtk/volume.cxx b/src/avtk/volume.cxx
index 8c8a524..0e17a39 100644
--- a/src/avtk/volume.cxx
+++ b/src/avtk/volume.cxx
@@ -41,6 +41,8 @@ Volume::Volume(int _x, int _y, int _w, int _h, const char *_label ):
   ampR = 0;
   compress = 0;
   value( 0.78f );
+
+  orientationHorizontal = false;
 }