diff --git a/indra/newview/llfloatermodelpreview.cpp b/indra/newview/llfloatermodelpreview.cpp
index cb58cfdd0aafb30acc5d229fc3de9a2e14c0fd0c..7705c1a76f0e4109b7e9d7bc87bcea2ee3da3ca5 100644
--- a/indra/newview/llfloatermodelpreview.cpp
+++ b/indra/newview/llfloatermodelpreview.cpp
@@ -3014,6 +3014,15 @@ void LLModelPreview::updateStatusMessages()
 	{
 		mFMP->childDisable("ok_btn");
 	}
+
+    if (mModelNoErrors && mLodsWithParsingError.empty())
+    {
+        mFMP->childEnable("calculate_btn");
+    }
+    else
+    {
+        mFMP->childDisable("calculate_btn");
+    }
 	
 	//add up physics triangles etc
 	S32 phys_tris = 0;