diff --git a/Source/cmLocalVisualStudio7Generator.cxx b/Source/cmLocalVisualStudio7Generator.cxx
index 7c2d72033..17c2704e2 100644
--- a/Source/cmLocalVisualStudio7Generator.cxx
+++ b/Source/cmLocalVisualStudio7Generator.cxx
@@ -22,6 +22,8 @@
 #include "cmCacheManager.h"
 #include "cmake.h"
 
+#include <ctype.h> // for isspace
+
 cmLocalVisualStudio7Generator::cmLocalVisualStudio7Generator()
 {
   this->Version = 7;