diff --git a/regressions/common.h b/regressions/common.h
index 0e682f4f..c779a933 100644
--- a/regressions/common.h
+++ b/regressions/common.h
@@ -43,6 +43,7 @@
 #include <pthread_np.h>
 #endif
 #elif defined(__MACH__)
+#include <errno.h>
 #include <mach/mach.h>
 #include <mach/thread_policy.h>
 #elif defined(__FreeBSD__)