diff --git a/dlls/kernel32/heap.c b/dlls/kernel32/heap.c
index b526af0..5abe2d4 100644
--- a/dlls/kernel32/heap.c
+++ b/dlls/kernel32/heap.c
@@ -809,34 +809,47 @@ SIZE_T WINAPI GlobalSize(HGLOBAL hmem)
 
    if (!hmem) return 0;
 
-   if(ISPOINTER(hmem))
-   {
-      retval=HeapSize(GetProcessHeap(), 0,  (LPVOID) hmem);
-   }
-   else
-   {
-      RtlLockHeap(GetProcessHeap());
-      pintern=HANDLE_TO_INTERN(hmem);
+   RtlLockHeap(GetProcessHeap());
 
-      if(pintern->Magic==MAGIC_GLOBAL_USED)
+   __TRY
+   {
+      if(ISPOINTER(hmem))
       {
-         if (!pintern->Pointer) /* handle case of GlobalAlloc( ??,0) */
-             retval = 0;
-         else
-         {
-             retval = HeapSize(GetProcessHeap(), 0,
-                         (char *)(pintern->Pointer) - HGLOBAL_STORAGE );
-             if (retval != (DWORD)-1) retval -= HGLOBAL_STORAGE;
-         }
+         retval=HeapSize(GetProcessHeap(), 0,  (LPVOID) hmem);
       }
       else
       {
-         WARN("invalid handle %p (Magic: 0x%04x)\n", hmem, pintern->Magic);
-         SetLastError(ERROR_INVALID_HANDLE);
-         retval=0;
+         pintern=HANDLE_TO_INTERN(hmem);
+
+         if(pintern->Magic==MAGIC_GLOBAL_USED)
+         {
+            if (!pintern->Pointer) /* handle case of GlobalAlloc( ??,0) */
+               retval = 0;
+            else
+            {
+               retval = HeapSize(GetProcessHeap(), 0,
+                                (char *)(pintern->Pointer) - HGLOBAL_STORAGE );
+               if (retval != (DWORD)-1) retval -= HGLOBAL_STORAGE;
+            }
+         }
+         else
+         {
+            WARN("invalid handle %p (Magic: 0x%04x)\n", hmem, pintern->Magic);
+            SetLastError(ERROR_INVALID_HANDLE);
+            retval=0;
+         }
       }
-      RtlUnlockHeap(GetProcessHeap());
    }
+   __EXCEPT_PAGE_FAULT
+   {
+      /* handle was invalid, crashed on access to pintern->Magic */
+      SetLastError(ERROR_INVALID_HANDLE);
+      retval = 0;
+   }
+   __ENDTRY
+
+   RtlUnlockHeap(GetProcessHeap());
+
    /* HeapSize returns 0xffffffff on failure */
    if (retval == 0xffffffff) retval = 0;
    return retval;
diff --git a/dlls/kernel32/tests/heap.c b/dlls/kernel32/tests/heap.c
old mode 100644
new mode 100755
index 34393e8..2939862
--- a/dlls/kernel32/tests/heap.c
+++ b/dlls/kernel32/tests/heap.c
@@ -197,6 +197,13 @@ START_TEST(heap)
     res = GlobalUnlock(gbl);
     ok(res == 1, "Expected 1, got %d\n", res);
 
+    /* GlobalSize on an invalid handle */
+    SetLastError(MAGIC_DEAD);
+    size = GlobalSize((HGLOBAL)0xc042);
+    ok(size == 0, "Expected 0, got %ld\n", size);
+    ok(GetLastError() == ERROR_INVALID_HANDLE,
+       "Expected ERROR_INVALID_HANDLE, got %d\n", GetLastError());
+
     /* ####################################### */
     /* Local*() functions */
     gbl = LocalAlloc(LMEM_MOVEABLE, 0);
-- 
1.4.4.2