diff --git a/auto/sources b/auto/sources
index fa2b2df..1e8790f 100644
--- a/auto/sources
+++ b/auto/sources
@@ -88,6 +88,7 @@
 
 UNIX_SRCS="$CORE_SRCS $EVENT_SRCS \
             src/os/unix/ngx_time.c \
+            src/os/unix/ngx_errno.c \
             src/os/unix/ngx_sendv.c \
             src/os/unix/ngx_files.c \
             src/os/unix/ngx_socket.c \