diff --git a/src/os2/window.cpp b/src/os2/window.cpp
index 6073949ccb..86716f40b3 100644
--- a/src/os2/window.cpp
+++ b/src/os2/window.cpp
@@ -2154,7 +2154,7 @@ MRESULT wxWindow::OS2WindowProc(
 
         // wxFrame specific message
         case WM_MINMAXFRAME:
-            bProcessed = HandleGetMinMaxInfo((PSWP)lParam);
+            bProcessed = HandleGetMinMaxInfo((PSWP)wParam);
             break;
 
         case WM_SYSVALUECHANGED: