diff --git a/src/io.c b/src/io.c
index bcbec23..6f87407 100644
--- a/src/io.c
+++ b/src/io.c
@@ -34,6 +34,7 @@
  *
  */
 
+#include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
diff --git a/src/strings.c b/src/strings.c
index 1af5e63..816ddc1 100644
--- a/src/strings.c
+++ b/src/strings.c
@@ -34,6 +34,8 @@
  *
  */
 
+#include <stdarg.h>
+
 #include "calcurse.h"
 
 #define STRING_INITIAL_BUFSIZE 128
diff --git a/src/utils.c b/src/utils.c
index 588dc8d..9d131ad 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -35,6 +35,7 @@
  */
 
 #include <time.h>
+#include <stdarg.h>
 #include <string.h>
 #include <strings.h>
 #include <stdlib.h>