diff --git a/lib/isc/win32/thread.c b/lib/isc/win32/thread.c
index d44f0683a4..b2fdd85514 100644
--- a/lib/isc/win32/thread.c
+++ b/lib/isc/win32/thread.c
@@ -17,6 +17,8 @@
 
 #include <config.h>
 
+#include <process.h>
+
 #include <isc/thread.h>
 
 isc_result_t