diff --git a/libguile/fluids.c b/libguile/fluids.c
index 601ca8b93..cc20eed64 100644
--- a/libguile/fluids.c
+++ b/libguile/fluids.c
@@ -42,6 +42,7 @@
 #include "_scm.h"
 #include "print.h"
 #include "smob.h"
+#include "genio.h"
 #include "dynwind.h"
 #include "fluids.h"
 #include "alist.h"
diff --git a/libguile/guardians.c b/libguile/guardians.c
index b929ea2c2..3cb0be850 100644
--- a/libguile/guardians.c
+++ b/libguile/guardians.c
@@ -56,6 +56,7 @@
 #include "_scm.h"
 #include "print.h"
 #include "smob.h"
+#include "genio.h"
 
 #include "guardians.h"
 
diff --git a/libguile/srcprop.c b/libguile/srcprop.c
index 409d2b8f3..25f08f97c 100644
--- a/libguile/srcprop.c
+++ b/libguile/srcprop.c
@@ -46,6 +46,7 @@
 #include <stdio.h>
 #include "_scm.h"
 #include "smob.h"
+#include "genio.h"
 #include "alist.h"
 #include "debug.h"
 #include "hashtab.h"
diff --git a/libguile/threads.c b/libguile/threads.c
index e7fffc865..55e7c9477 100644
--- a/libguile/threads.c
+++ b/libguile/threads.c
@@ -63,6 +63,7 @@
 #include "_scm.h"
 #include "dynwind.h"
 #include "smob.h"
+#include "genio.h"
 
 #include "threads.h"