diff --git a/Socket/Protocols/INet/INet4Address.cc b/Socket/Protocols/INet/INet4Address.cc
index 5d503092d13ff7794ebcb5a170ecd0e278a93c8e..2bc919881ae61a61ecaf15c9ea16de1acb982889 100644
--- a/Socket/Protocols/INet/INet4Address.cc
+++ b/Socket/Protocols/INet/INet4Address.cc
@@ -31,7 +31,7 @@
 #include <netdb.h>
 #include <sys/socket.h>
 #include <boost/lexical_cast.hpp>
-#ifd defined(_REENTRANT) && !defined(__GLIBC__)
+#if defined(_REENTRANT) && !defined(__GLIBC__)
 #include <boost/thread/mutex.hpp>
 #endif