diff --git a/msdos/ioports.c b/msdos/ioports.c
index 3f667fa1e5f..beaea7bc632 100644
--- a/msdos/ioports.c
+++ b/msdos/ioports.c
@@ -21,6 +21,7 @@
 #include "dosexe.h"
 #include "options.h"
 #include "debug.h"
+#include "miscemu.h"
 
 static WORD tmr_8253_countmax[3] = {0xffff, 0x12, 1}; /* [2] needs to be 1 ! */
 /* if byte_toggle is TRUE, then hi byte has already been written */