diff --git a/speed_test.asm b/speed_test.asm
index d9dc599..b94b39d 100644
--- a/speed_test.asm
+++ b/speed_test.asm
@@ -1844,6 +1844,7 @@ sa1_clock_finish_16:
 	sta $2251
 	asl
 	lda.w #63018	; 8.16 fixed point. ==> 315.0 / 88.0 * 1000000 * 6 / (262 * 1364) * 16 / 1000 * 65536
+	sta $4a		; save multiplier
 	bra sa1_clock_finish_continue
 	
 sa1_clock_finish:
@@ -1851,28 +1852,53 @@ sa1_clock_finish:
 	inc
 	sta $46
 	sta $2251
-	asl
+	asl		; save sign bit for later, adjustment needed for unsigned multiplication
 	lda.w #59079	; 8.16 fixed point. ==> 315.0 / 88.0 * 1000000 * 6 / (262 * 1364) * 15 / 1000 * 65536
+	sta $4a		; save multiplier
 .continue		; +/- 0.9 kHz resolution (or 0.00090 MHz)
 	sta $2253
 	ldy #$01
-	bcs +
-	lda $46
-+	ldx $2307
+	ldx $2307
 	stx $48
 	ldx $2306
-	clc
-	adc $2308
+	lda $2308
+	bcc +		; if loop counter was "signed negative" (>32767), add the other factor
+	clc		; to the upper 16 bits of the result to turn the signed multiplication
+	adc $4a		; into an unsigned one => add the fixed multiplier.
++	clc		; fixed multiplier (59079 or 63018) is always "signed negative"
+	adc $46		; so always adjust => always add the loop counter.
 	sty $2250
+	pha
+	lsr		; halve the dividend to make sure it is signed positive
 	sta $2251
-	lda.w #10000
+	lda.w #10000	; divisor is known signed positive (10000)
 	sta $2253
 	nop
 	xba
 	lda $2306
-	sta $46
+	asl
+	sta $46		; quotient
 	lda $2308
-	sta $2251
+	asl
+	sta $4a		; remainder
+	pla		; get the original dividend
+	ror		; check lsb
+	bcc +
+	inc $4a		; adjust remainder if lsb was set in dividend
++	lda $4a		; it might now be equal to the divisor
+	cmp.w #10000
+	bcc +		; if remainder is smaller than divisor, we're done.
+			; otherwise adjust results:
+			; e.g. 50001/10000 => 25000/10000 => q=2, r=5000
+			; double both => q=4, r=10000.
+			; original lsb of dividend was 1 => add to remainder => r=10001.
+			; since the remainder is >= 10000 increase the quotient by one and
+			; subtract the divisor from the remainder (modulo operation):
+			; q=5; r=(10001-10000)=1.
+	inc $46		; increase quotient
+	sec
+	sbc.w #10000	; adjust remainder to be less than divisor
++	sta $2251
 	lda.w #100
 	sta $2253
 	nop