--- a/make.c
+++ b/make.c
@@ -139,6 +139,8 @@
 static int MakeBuildChild(void *, void *);
 static int MakeBuildParent(void *, void *);
 
+FILE *debug_file;
+
 MAKE_ATTR_DEAD static void
 make_abort(GNode *gn, int line)
 {
--- a/make.h
+++ b/make.h
@@ -464,7 +464,7 @@
  *	There is one bit per module.  It is up to the module what debug
  *	information to print.
  */
-FILE *debug_file;		/* Output written here - default stdout */
+extern FILE *debug_file;		/* Output written here - default stdout */
 extern int debug;
 #define	DEBUG_ARCH	0x00001
 #define	DEBUG_COND	0x00002