diff --git a/src/osdep/dos/dos.c b/src/osdep/dos/dos.c
index 24348dc9d..6f33a73e6 100644
--- a/src/osdep/dos/dos.c
+++ b/src/osdep/dos/dos.c
@@ -1013,15 +1013,11 @@ void os_seed_random(unsigned char **pool, int *pool_size)
 	*pool_size = RANDOM_POOL_SIZE;
 }
 
+#ifdef CONFIG_ECMASCRIPT
 _go32_dpmi_seginfo OldISR, NewISR;
 #define TIMER 8
 //Simple Example of chaining interrupt handlers
 //Adopted from Matthew Mastracci's code
-
-#include <pc.h>
-#include <dpmi.h>
-#include <go32.h>
-
 //macros by Shawn Hargreaves from the Allegro library for locking
 //functions and variables.
 #define LOCK_VARIABLE(x)    _go32_dpmi_lock_data((void *)&x,(long)sizeof(x));
@@ -1030,15 +1026,14 @@ _go32_dpmi_seginfo OldISR, NewISR;
 static void
 TickHandler(void)
 {
-#ifdef CONFIG_ECMASCRIPT
 	static int internal = 0;
 
 	if (internal++ >= 19) {
 		internal = 0;
 		check_heartbeats(NULL);
 	}
-#endif
 }
+#endif
 
 void init_osdep(void)
 {
@@ -1071,6 +1066,7 @@ void init_osdep(void)
 	sa.sa_flags = SA_RESTART;
 	EINTRLOOP(rs, sigaction(SIGINT, &sa, NULL));
 
+#ifdef CONFIG_ECMASCRIPT
 	LOCK_FUNCTION(TickHandler);
 	LOCK_FUNCTION(check_heartbeats);
 //load the address of the old timer ISR into the OldISR structure
@@ -1083,14 +1079,16 @@ void init_osdep(void)
 //timer ISR
 //will be called, then the new timer ISR
 	_go32_dpmi_chain_protected_mode_interrupt_vector(TIMER, &NewISR);
+#endif
 }
 
 void terminate_osdep(void)
 {
 	if (screen_backbuffer)
 		mem_free(screen_backbuffer);
-
+#ifdef CONFIG_ECMASCRIPT
 	_go32_dpmi_set_protected_mode_interrupt_vector(TIMER, &OldISR);
+#endif
 }
 
 #define LINKS_BIN_SEARCH(entries, eq, ab, key, result)                        \