diff --git a/core/bus.c b/core/bus.c
index a03d9e1..2288552 100644
--- a/core/bus.c
+++ b/core/bus.c
@@ -153,12 +153,18 @@ static void busRead(VB *sim, uint32_t address, int type, int32_t *value) {
 
         case 0: /* VIP */
             vipRead(sim, address, type, value);
+            switch (type) {
+                case VB_S8 : *value = (int8_t ) *value; break;
+                case VB_S16: *value = (int16_t) *value; break;
+            }
             break;
 
         case 1: break; /* VSU */
 
         case 2: /* Misc. I/O */
             *value = busReadMisc(sim, address, type);
+            if (type == VB_S8)
+                *value = (int8_t) *value;
             break;
 
         case 3: break; /* Unmapped */