diff --git a/apps/zasm/main.asm b/apps/zasm/main.asm
index 3e528d1..6f05dce 100644
--- a/apps/zasm/main.asm
+++ b/apps/zasm/main.asm
@@ -88,10 +88,14 @@ incOutputOffset:
 	pop	de
 	ret
 
+; Repeatedly reads lines from IO, assemble them and spit the binary code in
+; IO. Z is set on success, unset on error. DE contains the last line number to
+; be read (first line is 1).
 zasmParseFile:
-	ld	hl, 0
-	ld	(curOutputOffset), hl
+	ld	de, 0
+	ld	(curOutputOffset), de
 .loop:
+	inc	de
 	call	ioReadLine
 	or	a		; is A 0?
 	ret	z		; We have EOF
diff --git a/tools/emul/zasm.c b/tools/emul/zasm.c
index 3785be3..891bcf4 100644
--- a/tools/emul/zasm.c
+++ b/tools/emul/zasm.c
@@ -119,6 +119,7 @@ int main()
     }
 #endif
     fflush(stdout);
+    fprintf(stderr, "Ended with A=%d DE=%d\n", cpu.R1.br.A, cpu.R1.wr.DE);
     return 0;
 }