diff --git a/Source/DSPSpy/tests/dsp_base.inc b/Source/DSPSpy/tests/dsp_base.inc
index dd9ae2df76..664d0a0333 100644
--- a/Source/DSPSpy/tests/dsp_base.inc
+++ b/Source/DSPSpy/tests/dsp_base.inc
@@ -86,10 +86,10 @@ main:
 	lrri	$ix1, @$ar0
 	lrri	$ix2, @$ar0
 	lrri	$ix3, @$ar0
-	lrri	$r08, @$ar0
-	lrri	$r09, @$ar0
-	lrri	$r10, @$ar0
-	lrri	$r11, @$ar0
+	lrri	$wr0, @$ar0
+	lrri	$wr1, @$ar0
+	lrri	$wr2, @$ar0
+	lrri	$wr3, @$ar0
 	lrri	$st0, @$ar0
 	lrri	$st1, @$ar0
 	lrri	$st2, @$ar0
@@ -206,8 +206,8 @@ irq:
 	andcf	$ac1.m, #0x8000
 	jlz		irq
 	si		@DMBH, #0x8BAD
-	sr		@DMBL, $r11
-;sr		@DMBL, $ac0.m	
+	sr		@DMBL, $wr3     ; ???
+	;sr		@DMBL, $ac0.m	
 	si		@DIRQ, #0x0001
 	halt
 	
@@ -228,10 +228,10 @@ send_back:
 	srri	@$ar0, $ix1
 	srri	@$ar0, $ix2
 	srri	@$ar0, $ix3
-	srri	@$ar0, $r08
-	srri	@$ar0, $r09
-	srri	@$ar0, $r10
-	srri	@$ar0, $r11
+	srri	@$ar0, $wr0
+	srri	@$ar0, $wr1
+	srri	@$ar0, $wr2
+	srri	@$ar0, $wr3
 	srri	@$ar0, $st0
 	srri	@$ar0, $st1
 	srri	@$ar0, $st2
@@ -294,10 +294,10 @@ dma_copy:
 	lrri	$ix1, @$ar0
 	lrri	$ix2, @$ar0
 	lrri	$ix3, @$ar0
-	lrri	$r08, @$ar0
-	lrri	$r09, @$ar0
-	lrri	$r10, @$ar0
-	lrri	$r11, @$ar0
+	lrri	$wr0, @$ar0
+	lrri	$wr1, @$ar0
+	lrri	$wr2, @$ar0
+	lrri	$wr3, @$ar0
 	lrri	$st0, @$ar0
 	lrri	$st1, @$ar0
 	lrri	$st2, @$ar0
diff --git a/Source/DSPSpy/tests/mul_test.ds b/Source/DSPSpy/tests/mul_test.ds
new file mode 100644
index 0000000000..030d1cce0a
--- /dev/null
+++ b/Source/DSPSpy/tests/mul_test.ds
@@ -0,0 +1,58 @@
+; This test checks the effect of SET15 on multiplications.
+incdir  "tests"
+include "dsp_base.inc"
+
+SET40
+LRI     $AC0.M, #0x1234
+LRI     $AC0.L, #0x5678
+SET16
+
+m2
+CLR     $ACC0
+LRI     $AX0.L, #0xFFFF
+LRI		$AX1.L, #0x100
+MULX	$AX0.L, $AX1.L
+MULXAC	$AX0.L, $AX1.L, $ACC0
+call send_back
+
+CLR     $ACC0
+SET15	
+LRI     $AX0.L, #0xFFFF
+LRI		$AX1.L, #0x100
+MULX	$AX0.L, $AX1.L
+MULXAC	$AX0.L, $AX1.L, $ACC0
+CLR15	
+call send_back
+m0
+lri $AX0.L, #1
+lri $AX1.L, #2
+mulx $AX0.L, $AX1.L
+movp $ACC0
+call send_back  ; 1
+
+set15
+lri $AX0.L, #2
+lri $AX1.L, #4
+mulx $AX0.L, $AX1.L
+movp $ACC0
+clr15
+call send_back  ; 1
+
+m2
+lri $AX0.L, #1
+lri $AX1.L, #2
+mulx $AX0.L, $AX1.L
+movp $ACC0
+call send_back  ; 1
+
+set15
+lri $AX0.L, #2
+lri $AX1.L, #4
+mulx $AX0.L, $AX1.L
+movp $ACC0
+clr15
+call send_back  ; 1
+m0
+
+; We're done, DO NOT DELETE THIS LINE
+jmp end_of_test