diff --git a/libport/semaphore.hxx b/libport/semaphore.hxx
index bb2546d..38b0d8e 100644
--- a/libport/semaphore.hxx
+++ b/libport/semaphore.hxx
@@ -5,6 +5,7 @@
 # include "exception.hh"
 # include <sstream>
 # include <string>
+# include <cstring>
 
 namespace libport
 {