diff --git a/display/type340.c b/display/type340.c
index 89fd5085..e508bff3 100644
--- a/display/type340.c
+++ b/display/type340.c
@@ -144,12 +144,12 @@ ty340_set_dac(ty340word addr)
 #endif
 
 ty340word
-ty340_reset(void)
+ty340_reset(void *dptr)
 {
     struct type340 *u = UNIT(0);
 #ifndef TY340_NODISPLAY
     if (!u->initialized) {
-        display_init(DIS_TYPE340, 1, u); /* XXX check return? */
+        display_init(DIS_TYPE340, 1, dptr); /* XXX check return? */
         u->initialized = 1;
     }
 #endif
diff --git a/display/type340.h b/display/type340.h
index 48291973..7bb7af1a 100644
--- a/display/type340.h
+++ b/display/type340.h
@@ -46,7 +46,7 @@ typedef unsigned int ty340word;
 /*
  * calls from host into type340.c
  */
-ty340word ty340_reset(void);
+ty340word ty340_reset(void *);
 ty340word ty340_status(void);
 ty340word ty340_instruction(ty340word inst);
 void ty340_set_dac(ty340word addr);