diff --git a/include/errno.h b/include/errno.h
index 39426818e0..15ece2f97f 100644
--- a/include/errno.h
+++ b/include/errno.h
@@ -15,5 +15,10 @@ extern int errno;
 
 #ifdef CONFIG_ERRNO_STR
 const char *errno_str(int errno);
+#else
+static inline const char *errno_str(int errno)
+{
+	return 0;
+}
 #endif
 #endif /* _ERRNO_H */