diff --git a/include/error.h b/include/error.h
index 7239db85..acc9cfa9 100644
--- a/include/error.h
+++ b/include/error.h
@@ -32,6 +32,8 @@
 extern "C" {
 #endif
 
+#include <stdarg.h>
+
 /**
  *  \defgroup Error Error handling
  *  Error handling macros and functions.
diff --git a/include/output.h b/include/output.h
index 4a970dc4..b0878c04 100644
--- a/include/output.h
+++ b/include/output.h
@@ -32,6 +32,8 @@
 extern "C" {
 #endif
 
+#include <stdarg.h>
+
 /**
  *  \defgroup Output Output Interface
  *