Add an important missing blank.
diff --git a/PCbuild/build_tkinter.py b/PCbuild/build_tkinter.py
index a7205d0..574d768 100644
--- a/PCbuild/build_tkinter.py
+++ b/PCbuild/build_tkinter.py
@@ -25,7 +25,7 @@
 # Windows 2000 compatibility: WINVER 0x0500
 # http://msdn2.microsoft.com/en-us/library/aa383745.aspx
 NMAKE = ('nmake /nologo /f %s '
-    'COMPILERFLAGS=\"-DWINVER=0x0500 -D_WIN32_WINNT=0x0500 -DNTDDI_VERSION=NTDDI_WIN2KSP4\"'
+    'COMPILERFLAGS=\"-DWINVER=0x0500 -D_WIN32_WINNT=0x0500 -DNTDDI_VERSION=NTDDI_WIN2KSP4\" '
     '%s %s')
 
 def nmake(makefile, command="", **kw):