diff --git a/src/exiv2.cpp b/src/exiv2.cpp
index d6a45e1b..2684475d 100644
--- a/src/exiv2.cpp
+++ b/src/exiv2.cpp
@@ -47,7 +47,7 @@ EXIV2_RCSID("@(#) $Id$")
 #include <cassert>
 #include <cctype>
 
-#if EXV_HAVE_REGEX
+#ifdef EXV_HAVE_REGEX
 #include <regex.h>
 #endif