diff --git a/c64/kernal/iec/talk.s b/c64/kernal/iec/talk.s
index 36718097..f9726d4d 100644
--- a/c64/kernal/iec/talk.s
+++ b/c64/kernal/iec/talk.s
@@ -32,14 +32,12 @@ common_talk_listen: // common part of TALK and LISTEN
 
 	sta TBTCNT
 
-#if CONFIG_IEC_JIFFYDOS
+#if CONFIG_IEC_JIFFYDOS || CONFIG_IEC_DOLPHINDOS
 
-	// It seems that only TALK/LISTEN is used to detect the JiffyDOS support
-
-	lda #$FF // unknown protocol - check what is supported
+	lda #$FF                           // force JiffyDOS detection, clear DolphinDOS mark
 	sta IECPROTO
 
-#endif // CONFIG_IEC_JIFFYDOS
+#endif
 
 	jmp iec_tx_command
 
diff --git a/c64/kernal/iec/unlsn.s b/c64/kernal/iec/unlsn.s
index 4681c089..857956c6 100644
--- a/c64/kernal/iec/unlsn.s
+++ b/c64/kernal/iec/unlsn.s
@@ -18,9 +18,9 @@ UNLSN:
 	// According to serial-bus.pdf (page 15) this routine flushes the IEC out buffer
 	jsr iec_tx_flush
 
-#if CONFIG_IEC_JIFFYDOS
+#if CONFIG_IEC_JIFFYDOS || CONFIG_IEC_DOLPHINDOS
 
-	lda #$FF // XXX
+	lda #$FF                           // do not use JiffyDOS / DolphinDOS anymore, trigger JiffyDOS detection
 	sta IECPROTO
 
 #endif
diff --git a/c64/kernal/iec/untlk.s b/c64/kernal/iec/untlk.s
index d8db0fb1..e4bb2717 100644
--- a/c64/kernal/iec/untlk.s
+++ b/c64/kernal/iec/untlk.s
@@ -18,9 +18,9 @@ UNTLK:
 	// According to serial-bus.pdf (page 15) this routine flushes the IEC out buffer
 	jsr iec_tx_flush
 
-#if CONFIG_IEC_JIFFYDOS
+#if CONFIG_IEC_JIFFYDOS || CONFIG_IEC_DOLPHINDOS
 
-	lda #$FF // XXX
+	lda #$FF                           // do not use JiffyDOS / DolphinDOS anymore, trigger JiffyDOS detection
 	sta IECPROTO
 
 #endif