diff --git a/src/io.c b/src/io.c
index 9554c971d..45dd4cb3d 100644
--- a/src/io.c
+++ b/src/io.c
@@ -445,10 +445,10 @@ outb(uint16_t port, uint8_t val)
         }
     }
 
-    if (!found) {
+    if (!found || (port == 0x84)) {
         cycles -= io_delay;
 #ifdef USE_DYNAREC
-        if (cpu_use_dynarec && ((port == 0xeb) || (port == 0xed)))
+        if (cpu_use_dynarec && ((port == 0x84) || (port == 0xeb) || (port == 0xed)))
             update_tsc();
 #endif
     }