diff --git a/mailnews/base/src/nsMsgPtrArray.cpp b/mailnews/base/src/nsMsgPtrArray.cpp
index 46b0056f3e28..4e53fbbc357c 100644
--- a/mailnews/base/src/nsMsgPtrArray.cpp
+++ b/mailnews/base/src/nsMsgPtrArray.cpp
@@ -38,10 +38,6 @@
 static char THIS_FILE[] = __FILE__;
 #endif
 
-#ifdef XP_WIN16
-#define SIZE_T_MAX 0xFF80		// a little less than 64K, the max alloc size on win16.
-#define MAX_ARR_ELEMS SIZE_T_MAX/sizeof(void*)
-#endif
 /////////////////////////////////////////////////////////////////////////////
 
 XPPtrArray::XPPtrArray()