diff --git a/src/Make_mvc.mak b/src/Make_mvc.mak
index 18fd327..c2567d7 100644
--- a/src/Make_mvc.mak
+++ b/src/Make_mvc.mak
@@ -193,10 +193,6 @@
 CPU = i386
 !endif # !PROCESSOR_ARCHITECTURE
 
-!if ("$(CPU)" == "AMD64") || ("$(CPU)" == "IA64")
-DEFINES=$(DEFINES) /Wp64
-!endif
-
 # Build a retail version by default
 
 !if "$(DEBUG)" != "yes"
@@ -211,6 +207,11 @@
 
 !include <Win32.mak>
 
+# Turn on Win64 compatibility warnings for 32-bit compiler in VC8. (/Wp64 is
+# deprecated in VC9.)
+!if ("$(MSVCVER)" == "8.0") 
+DEFINES=$(DEFINES) /Wp64
+!endif
 
 #>>>>> path of the compiler and linker; name of include and lib directories
 # PATH = c:\msvc20\bin;$(PATH)