diff --git a/src/msw/listctrl.cpp b/src/msw/listctrl.cpp
index f19fcfb670..b55dddf5d2 100644
--- a/src/msw/listctrl.cpp
+++ b/src/msw/listctrl.cpp
@@ -465,7 +465,7 @@ wxTextCtrl* wxListCtrl::GetEditControl(void) const
 bool wxListCtrl::GetItem(wxListItem& info) const
 {
   LV_ITEM lvItem;
-#ifdef __MINGW32__
+#ifdef __GNUWIN32__
   memset(&lvItem, 0, sizeof(lvItem));
 #else
   ZeroMemory(&lvItem, sizeof(lvItem)); // must set all fields to 0
diff --git a/src/msw/tooltip.cpp b/src/msw/tooltip.cpp
index 7829ec50e9..199c42a0a1 100644
--- a/src/msw/tooltip.cpp
+++ b/src/msw/tooltip.cpp
@@ -47,7 +47,11 @@ public:
     wxToolInfo(wxWindow *win)
     {
         // initialize all members
+#ifdef __GNUWIN32__
+        memset(this, 0, sizeof(TOOLINFO));
+#else
         ::ZeroMemory(this, sizeof(TOOLINFO));
+#endif
 
         cbSize = sizeof(TOOLINFO);
         uFlags = TTF_IDISHWND;
diff --git a/src/msw/utilsexc.cpp b/src/msw/utilsexc.cpp
index ade6c3077a..730828e34e 100644
--- a/src/msw/utilsexc.cpp
+++ b/src/msw/utilsexc.cpp
@@ -211,7 +211,12 @@ long wxExecute(const wxString& command, bool sync, wxProcess *handler)
 #else // 1
     // create the process
     STARTUPINFO si;
+#ifdef __GNUWIN32__
+    memset(&si, 0, sizeof(si));
+#else
     ::ZeroMemory(&si, sizeof(si));
+#endif
+
     si.cb = sizeof(si);
 
     PROCESS_INFORMATION pi;