diff --git a/core/asm/asm_test.go b/core/asm/asm_test.go
index 92b26b67a5..cd7520ec63 100644
--- a/core/asm/asm_test.go
+++ b/core/asm/asm_test.go
@@ -22,53 +22,37 @@ import (
 	"encoding/hex"
 )
 
-// Tests disassembling the instructions for valid evm code
-func TestInstructionIteratorValid(t *testing.T) {
-	cnt := 0
-	script, _ := hex.DecodeString("61000000")
+// Tests disassembling instructions
+func TestInstructionIterator(t *testing.T) {
+	for i, tc := range []struct {
+		want    int
+		code    string
+		wantErr string
+	}{
+		{2, "61000000", ""},                             // valid code
+		{0, "6100", "incomplete push instruction at 0"}, // invalid code
+		{2, "5900", ""},                                 // push0
+		{0, "", ""},                                     // empty
 
-	it := NewInstructionIterator(script)
-	for it.Next() {
-		cnt++
-	}
-
-	if err := it.Error(); err != nil {
-		t.Errorf("Expected 2, but encountered error %v instead.", err)
-	}
-	if cnt != 2 {
-		t.Errorf("Expected 2, but got %v instead.", cnt)
-	}
-}
-
-// Tests disassembling the instructions for invalid evm code
-func TestInstructionIteratorInvalid(t *testing.T) {
-	cnt := 0
-	script, _ := hex.DecodeString("6100")
-
-	it := NewInstructionIterator(script)
-	for it.Next() {
-		cnt++
-	}
-
-	if it.Error() == nil {
-		t.Errorf("Expected an error, but got %v instead.", cnt)
-	}
-}
-
-// Tests disassembling the instructions for empty evm code
-func TestInstructionIteratorEmpty(t *testing.T) {
-	cnt := 0
-	script, _ := hex.DecodeString("")
-
-	it := NewInstructionIterator(script)
-	for it.Next() {
-		cnt++
-	}
-
-	if err := it.Error(); err != nil {
-		t.Errorf("Expected 0, but encountered error %v instead.", err)
-	}
-	if cnt != 0 {
-		t.Errorf("Expected 0, but got %v instead.", cnt)
+	} {
+		var (
+			have    int
+			code, _ = hex.DecodeString(tc.code)
+			it      = NewInstructionIterator(code)
+		)
+		for it.Next() {
+			have++
+		}
+		var haveErr = ""
+		if it.Error() != nil {
+			haveErr = it.Error().Error()
+		}
+		if haveErr != tc.wantErr {
+			t.Errorf("test %d: encountered error: %q want %q", i, haveErr, tc.wantErr)
+			continue
+		}
+		if have != tc.want {
+			t.Errorf("wrong instruction count, have %d want %d", have, tc.want)
+		}
 	}
 }
diff --git a/core/vm/opcodes.go b/core/vm/opcodes.go
index 969354cf59..26523e53ce 100644
--- a/core/vm/opcodes.go
+++ b/core/vm/opcodes.go
@@ -25,11 +25,7 @@ type OpCode byte
 
 // IsPush specifies if an opcode is a PUSH opcode.
 func (op OpCode) IsPush() bool {
-	switch op {
-	case PUSH1, PUSH2, PUSH3, PUSH4, PUSH5, PUSH6, PUSH7, PUSH8, PUSH9, PUSH10, PUSH11, PUSH12, PUSH13, PUSH14, PUSH15, PUSH16, PUSH17, PUSH18, PUSH19, PUSH20, PUSH21, PUSH22, PUSH23, PUSH24, PUSH25, PUSH26, PUSH27, PUSH28, PUSH29, PUSH30, PUSH31, PUSH32:
-		return true
-	}
-	return false
+	return PUSH0 <= op && op <= PUSH32
 }
 
 // 0x0 range - arithmetic ops.