diff --git a/chip-z80/support.js b/chip-z80/support.js
index 2d6232c..8f44d6b 100644
--- a/chip-z80/support.js
+++ b/chip-z80/support.js
@@ -47,9 +47,9 @@ function halfStep(){
     eval(clockTriggers[cycle]);
     if (clk) {setLow('clk'); }
     else {setHigh('clk'); }
-    // DMB: It's almost certainly wrong to execute the on both clock edges
+    // DMB: It's almost certainly wrong to execute these on both clock edges
     handleBusRead();
-    handleBusWrite;
+    handleBusWrite();
 }
 
 function goUntilSyncOrWrite(){
diff --git a/chip-z80/testprogram.js b/chip-z80/testprogram.js
index 85814c2..5c85bdd 100644
--- a/chip-z80/testprogram.js
+++ b/chip-z80/testprogram.js
@@ -16,6 +16,11 @@ readTriggers[0x8000]="var c=consolegetc; consolegetc=undefined; (c)";
 
 testprogram = [
     0xD9,                    // EXX
+    0x21, 0x00, 0x01,        // LD HL,$0100
+    0x36, 0xCC,              // LD (HL),$CC
+    0x00,                    // NOP
+    0x7E,                    // LD A, (HL)
+    0x00,                    // NOP
     0x21, 0x34, 0x12,        // LD HL,$1234
     0x31, 0xfe, 0xdc,        // LD SP,0xDCFE
     0xe5,                    // PUSH HL