diff --git a/panda/src/dxgsg9/dxShaderContext9.cxx b/panda/src/dxgsg9/dxShaderContext9.cxx
index e3992bea5d..c3b1970bd9 100644
--- a/panda/src/dxgsg9/dxShaderContext9.cxx
+++ b/panda/src/dxgsg9/dxShaderContext9.cxx
@@ -207,7 +207,7 @@ issue_parameters(GSG *gsg, int altered) {
 
         // Calculate how many elements to transfer; no more than it expects,
         // but certainly no more than we have.
-        int input_size = min(abs(spec._dim[0] * spec._dim[1] * spec._dim[2]), ptr_data->_size);
+        int input_size = min(abs(spec._dim[0] * spec._dim[1] * spec._dim[2]), (int)ptr_data->_size);
 
         CGparameter p = _cg_parameter_map[spec._id._seqno];
         switch (ptr_data->_type) {