diff --git a/include/env_callback.h b/include/env_callback.h
index 23bc650..8e500aa 100644
--- a/include/env_callback.h
+++ b/include/env_callback.h
@@ -7,6 +7,7 @@
 #ifndef __ENV_CALLBACK_H__
 #define __ENV_CALLBACK_H__
 
+#include <config.h>
 #include <env_flags.h>
 #include <linker_lists.h>
 #include <search.h>
diff --git a/include/env_default.h b/include/env_default.h
index 8ee500d..076ffdd 100644
--- a/include/env_default.h
+++ b/include/env_default.h
@@ -7,6 +7,7 @@
  * Andreas Heppel <aheppel@sysgo.de>
  */
 
+#include <config.h>
 #include <env_callback.h>
 #include <linux/stringify.h>
 
diff --git a/include/env_flags.h b/include/env_flags.h
index d785f87..2476043 100644
--- a/include/env_flags.h
+++ b/include/env_flags.h
@@ -7,6 +7,8 @@
 #ifndef __ENV_FLAGS_H__
 #define __ENV_FLAGS_H__
 
+#include <config.h>
+
 enum env_flags_vartype {
 	env_flags_vartype_string,
 	env_flags_vartype_decimal,