diff --git a/mozilla/js/src/config/WINNT5.0.mk b/mozilla/js/src/config/WINNT5.0.mk
index 15a5a6fd2d0..2b796a4f193 100644
--- a/mozilla/js/src/config/WINNT5.0.mk
+++ b/mozilla/js/src/config/WINNT5.0.mk
@@ -89,7 +89,7 @@ OPTIMIZER = $(WIN_DEBUG_CFLAGS)
 endif
 endif
 
-OS_CFLAGS = -D_X86_=1 -DXP_WIN -DXP_WIN32 -DWIN32 -D_WINDOWS -D_WIN32 $(WIN_CFLAGS)
+OS_CFLAGS = -D_X86_=1 -DXP_WIN -DXP_WIN32 -DWIN32 -D_WINDOWS -D_WIN32 -DWINVER=0x500 -D_WIN32_WINNT=0x500 $(WIN_CFLAGS)
 JSDLL_CFLAGS = -DEXPORT_JS_API
 OS_LIBS = -lm -lc
 
diff --git a/mozilla/js/src/config/WINNT5.1.mk b/mozilla/js/src/config/WINNT5.1.mk
index 15a5a6fd2d0..2b796a4f193 100644
--- a/mozilla/js/src/config/WINNT5.1.mk
+++ b/mozilla/js/src/config/WINNT5.1.mk
@@ -89,7 +89,7 @@ OPTIMIZER = $(WIN_DEBUG_CFLAGS)
 endif
 endif
 
-OS_CFLAGS = -D_X86_=1 -DXP_WIN -DXP_WIN32 -DWIN32 -D_WINDOWS -D_WIN32 $(WIN_CFLAGS)
+OS_CFLAGS = -D_X86_=1 -DXP_WIN -DXP_WIN32 -DWIN32 -D_WINDOWS -D_WIN32 -DWINVER=0x500 -D_WIN32_WINNT=0x500 $(WIN_CFLAGS)
 JSDLL_CFLAGS = -DEXPORT_JS_API
 OS_LIBS = -lm -lc
 
diff --git a/mozilla/js/src/config/WINNT5.2.mk b/mozilla/js/src/config/WINNT5.2.mk
index 15a5a6fd2d0..2b796a4f193 100644
--- a/mozilla/js/src/config/WINNT5.2.mk
+++ b/mozilla/js/src/config/WINNT5.2.mk
@@ -89,7 +89,7 @@ OPTIMIZER = $(WIN_DEBUG_CFLAGS)
 endif
 endif
 
-OS_CFLAGS = -D_X86_=1 -DXP_WIN -DXP_WIN32 -DWIN32 -D_WINDOWS -D_WIN32 $(WIN_CFLAGS)
+OS_CFLAGS = -D_X86_=1 -DXP_WIN -DXP_WIN32 -DWIN32 -D_WINDOWS -D_WIN32 -DWINVER=0x500 -D_WIN32_WINNT=0x500 $(WIN_CFLAGS)
 JSDLL_CFLAGS = -DEXPORT_JS_API
 OS_LIBS = -lm -lc