diff --git a/blockingconcurrentqueue.h b/blockingconcurrentqueue.h
index 4f64fae4..51df251a 100644
--- a/blockingconcurrentqueue.h
+++ b/blockingconcurrentqueue.h
@@ -26,6 +26,7 @@ extern "C" {
 #elif defined(__MACH__)
 #include <mach/mach.h>
 #elif defined(__unix__)
+#include <cerrno>
 #include <semaphore.h>
 #endif