diff --git a/c64/kernal/iec/iec_tx_byte.s b/c64/kernal/iec/iec_tx_byte.s
index 40259cbb..4cff6ad9 100644
--- a/c64/kernal/iec/iec_tx_byte.s
+++ b/c64/kernal/iec/iec_tx_byte.s
@@ -57,36 +57,11 @@ iec_tx_common_sendbit:
 
 #if CONFIG_IEC_JIFFYDOS
 
-	// Here is the place we can detect JiffyDOS protocol, by inserting a long delay
-	// (above 400us?) during sending command last bit, see:
-    // - https://sites.google.com/site/h2obsession/CBM/C128/JiffySoft128
-    // - https://github.com/rkrajnc/sd2iec/blob/master/src/iec.c
-    // The 'iec.s' suggests, that the drive should respond by pulling data
-
+	bne !+                             // branch if not sending the last bit
     lda IECPROTO
     bpl !+                             // branch if protocol is known
-    cpx #$00
-    bne !+                             // branch if not sending the last bit
-
-    ldy #$25                           // 400us is nearly 410 cycles on NTSC
-                                       // loop iteration below is 11 cycles,
-                                       // and several cycles were already used
-iec_jiffydos_detect_loop:
-	lda CIA2_PRA                       // 4 cycles
-	bpl iec_jiffydos_detected          // 2 cycles
-	dey                                // 2 cycles
-	bne iec_jiffydos_detect_loop       // 3 cycles if branch
-
-	lda #$00                           // normal protocol
-	beq iec_jiffydos_store_proto       // branch always
-
-iec_jiffydos_detected:
-	jsr iec_wait_for_data_release      // guessed from VICE logs
-	lda #$01                           // JiffyDOS protocol
-
-iec_jiffydos_store_proto:
-	sta IECPROTO
 
+    jsr jiffydos_detect
 !:
 #endif // CONFIG_IEC_JIFFYDOS
 
diff --git a/c64/kernal/iec_fast/jiffydos_detect.s b/c64/kernal/iec_fast/jiffydos_detect.s
new file mode 100644
index 00000000..40f19523
--- /dev/null
+++ b/c64/kernal/iec_fast/jiffydos_detect.s
@@ -0,0 +1,42 @@
+
+//
+// Helper routine for JiffyDOS detection
+//
+
+// Detection is done by inserting a long delay (above 400us?) during sending command last bit, see:
+// - https://sites.google.com/site/h2obsession/CBM/C128/JiffySoft128
+// - https://github.com/rkrajnc/sd2iec/blob/master/src/iec.c
+// The 'iec.s' suggests, that the drive should respond by pulling data
+
+
+
+#if CONFIG_IEC_JIFFYDOS
+
+
+jiffydos_detect:
+
+    ldy #$25                           // 400us is nearly 410 cycles on NTSC
+                                       // loop iteration below is 11 cycles,
+                                       // and several cycles were already used
+jiffydos_detect_loop:
+	lda CIA2_PRA                       // 4 cycles
+	bpl jiffydos_detected              // 2 cycles
+	dey                                // 2 cycles
+	bne jiffydos_detect_loop           // 3 cycles if branch
+
+	lda #$00                           // normal protocol
+	beq jiffydos_store_proto           // branch always
+
+jiffydos_detected:
+	jsr iec_wait_for_data_release      // guessed from VICE logs
+	lda #$01                           // JiffyDOS protocol
+
+	// FALLTROUGH
+
+jiffydos_store_proto:
+	sta IECPROTO
+
+	rts
+
+
+#endif // CONFIG_IEC_JIFFYDOS