diff --git a/libguile/null-threads.c b/libguile/null-threads.c
index fd9f189b1..aa6dbdfa1 100644
--- a/libguile/null-threads.c
+++ b/libguile/null-threads.c
@@ -23,6 +23,8 @@
 
 #include <stdlib.h>
 
+#include "libguile/scmconfig.h"
+
 
 #if SCM_USE_NULL_THREADS
 #include "null-threads.h"
diff --git a/libguile/null-threads.h b/libguile/null-threads.h
index a15bd21fb..88926fa2f 100644
--- a/libguile/null-threads.h
+++ b/libguile/null-threads.h
@@ -36,6 +36,8 @@
 #include <signal.h>
 #include <errno.h>
 
+#include "libguile/scm.h"
+
 /* Threads
 */
 typedef int scm_i_pthread_t;