1 files changed, 2 insertions, 0 deletions
diff --git a/mutex.c b/mutex.c
index 2f51144..d53c356 100644
--- a/mutex.c
+++ b/mutex.c
@@ -5,6 +5,8 @@
  * This translation unit implements mutual exclusion (mutex) primitives.
  */
 
+#include <errno.h>
+
 #include "pthread.h"
 #include "implement.h"