diff --git a/opensubdiv/osd/glslPatchBoundaryGregory.glsl b/opensubdiv/osd/glslPatchBoundaryGregory.glsl
index 9773734f..7c465280 100644
--- a/opensubdiv/osd/glslPatchBoundaryGregory.glsl
+++ b/opensubdiv/osd/glslPatchBoundaryGregory.glsl
@@ -441,6 +441,12 @@ void main()
 layout(quads) in;
 layout(cw) in;
 
+#ifdef OSD_FRACTIONAL_ODD_SPACING
+    layout(fractional_odd_spacing) in;
+#elif OSD_FRACTIONAL_EVEN_SPACING
+    layout(fractional_even_spacing) in;
+#endif
+
 in block {
     GregEvalVertex v;
 } inpt[];