diff --git a/src/configfile.c b/src/configfile.c
index 3ee878c..c7b8c36 100644
--- a/src/configfile.c
+++ b/src/configfile.c
@@ -26,6 +26,7 @@
 #include <unistd.h>
 #include <string.h>
 #include <assert.h>
+#include <errno.h>
 #include <regex.h>
 #include <glib.h>
 #include "configfile.h"
diff --git a/src/rs485.c b/src/rs485.c
index 31ab2ec..3c9280c 100644
--- a/src/rs485.c
+++ b/src/rs485.c
@@ -20,6 +20,7 @@
  */
 
 #include <stdio.h>
+#include <errno.h>
 #include <string.h>
 #include <sys/ioctl.h>
 #include "options.h"