diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5e794fb..6a2c425 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -103,7 +103,6 @@ SET(BAD_SRCS
     src/lpytab.c
     src/mnwevent.c
     src/mnxmeth.c
-    src/mouseif.c
     src/picture.c
     src/rawcolor.c
     src/rawrs232c.c
@@ -183,6 +182,7 @@ SET(MAIKO_SRCS
     src/miscn.c
     src/mkatom.c
     src/mkcell.c
+    src/mouseif.c
     src/mvs.c
     src/osmsg.c
     src/perrno.c
diff --git a/src/mouseif.c b/src/mouseif.c
index a3b279d..36786e3 100644
--- a/src/mouseif.c
+++ b/src/mouseif.c
@@ -37,6 +37,7 @@ extern void ThreeButtonHandler();
 extern void TwoButtonHandler();
 #endif /* DOS */
 
+#ifdef DOS
 /*****************************************************************/
 /*                       p r o b e m o u s e                     */
 /*                                                               */
@@ -59,6 +60,7 @@ int probemouse() {
     return (regs.x.bx);
   }
 }
+#endif
 
 void make_mouse_instance(MouseInterface mouse)
 {