diff --git a/src/Makefile b/src/Makefile
index c0a4cc3a..55237919 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -107,7 +107,7 @@ endif
 ifdef LINUX64
 LINUX=1
 NONX86=1
-64BIT=1
+X86_64=1
 endif
 
 ifdef HAIKU
@@ -182,7 +182,7 @@ endif #ifdef MINGW
 
 ifdef MINGW64
 MINGW=1
-64BIT=1
+X86_64=1
 include win32/Makefile.cfg
 endif #ifdef MINGW64
 
@@ -299,7 +299,7 @@ else
 endif
 endif
 
-ifdef 64BIT
+ifdef X86_64
 	M5=-march=nocona
 endif