diff --git a/example_basiccalculator2_test.go b/example_basiccalculator2_test.go
index de807eb..c5356d7 100644
--- a/example_basiccalculator2_test.go
+++ b/example_basiccalculator2_test.go
@@ -98,11 +98,11 @@ func (c *calculator) expr(p *parsekit.ParseAPI) {
 	var pc, a = parsekit.C, parsekit.A
 	if p.Handle(c.term) {
 		for p.On(pc.Any(a.Add, a.Subtract)).Skip() {
-			c.interpreter.pushOperator(p.LastMatch)
+			op := p.LastMatch
 			if !p.Handle(c.term) {
 				return
 			}
-			c.interpreter.eval()
+			c.interpreter.eval(op)
 		}
 	}
 
@@ -116,11 +116,11 @@ func (c *calculator) term(p *parsekit.ParseAPI) {
 	var pc, a = parsekit.C, parsekit.A
 	if p.Handle(c.factor) {
 		for p.On(pc.Any(a.Multiply, a.Divide)).Skip() {
-			c.interpreter.pushOperator(p.LastMatch)
+			op := p.LastMatch
 			if !p.Handle(c.factor) {
 				return
 			}
-			c.interpreter.eval()
+			c.interpreter.eval(op)
 		}
 	}
 
@@ -164,9 +164,8 @@ func (c *calculator) factor(p *parsekit.ParseAPI) {
 // ---------------------------------------------------------------------------
 
 type stackFrame struct {
-	a  float64
-	b  float64
-	op func(a, b float64) float64
+	a float64
+	b float64
 }
 
 type interpreter struct {
@@ -175,51 +174,38 @@ type interpreter struct {
 	result float64
 }
 
-func (i *interpreter) push() *stackFrame {
+func (i *interpreter) push() {
 	f := &stackFrame{}
-	i.stack = append(i.stack, f)
-	i.top = f
-	i.pushOperator("VAL")
-	return f
+	i.top, i.stack = f, append(i.stack, f)
 }
 
-func (i *interpreter) pop() float64 {
-	value := i.eval()
+func (i *interpreter) pop() {
+	popped := i.top
 	i.stack = i.stack[0 : len(i.stack)-1]
 	if len(i.stack) > 0 {
 		i.top = i.stack[len(i.stack)-1]
-		i.pushValue(value)
+		i.pushValue(popped.b)
 	} else {
-		i.result = i.top.b
-		i.top = nil
+		i.result = popped.b
 	}
-	return value
 }
 
 func (i *interpreter) pushValue(value float64) {
 	i.top.a, i.top.b = i.top.b, value
 }
 
-func (i *interpreter) pushOperator(op string) {
+func (i *interpreter) eval(op string) float64 {
+	value := i.top.a
 	switch op {
-	case "VAL":
-		i.top.op = func(a, b float64) float64 { return b }
 	case "+":
-		i.top.op = func(a, b float64) float64 { return a + b }
+		value += i.top.b
 	case "-":
-		i.top.op = func(a, b float64) float64 { return a - b }
+		value -= i.top.b
 	case "*":
-		i.top.op = func(a, b float64) float64 { return a * b }
+		value *= i.top.b
 	case "/":
-		i.top.op = func(a, b float64) float64 { return a / b }
-	default:
-		panic(fmt.Sprintf("Unhandled op name: %s", op))
+		value /= i.top.b
 	}
-}
-
-func (i *interpreter) eval() float64 {
-	value := i.top.op(i.top.a, i.top.b)
-	i.pushValue(value)
-	i.pushOperator("VAL")
+	i.top.b = value
 	return value
 }
diff --git a/parsehandler.go b/parsehandler.go
index 0020844..001d297 100644
--- a/parsehandler.go
+++ b/parsehandler.go
@@ -68,7 +68,7 @@ func (p *ParseAPI) checkForLoops() {
 	id := fmt.Sprintf("%s:%d", file, line)
 	if _, ok := p.loopCheck[id]; ok {
 		caller := runtime.FuncForPC(pc)
-		panic(fmt.Sprintf("Loop detected in parser in %s at %s, line %d", caller.Name(), file, line))
+		panic(fmt.Sprintf("Loop detected in parser in %s at %s", caller.Name(), id))
 	}
 	p.loopCheck[id] = true
 }
diff --git a/parsehandler_test.go b/parsehandler_test.go
index cf654aa..487a39e 100644
--- a/parsehandler_test.go
+++ b/parsehandler_test.go
@@ -1,7 +1,6 @@
 package parsekit_test
 
 import (
-	"fmt"
 	"testing"
 
 	"git.makaay.nl/mauricem/go-parsekit"
@@ -105,7 +104,7 @@ func TestGivenLoopingParserDefinition_ParserPanics(t *testing.T) {
 		func() { parser.Execute("Het houdt niet op, niet vanzelf") },
 		"Loop detected in parser in git.makaay.nl/mauricem/go-parsekit_test." +
 			"(*parserWithLoop).second at /home/ubuntu/Projects/Parsekit/go-parsekit" +
-			"/parsehandler_test.go, line 87"})
+			"/parsehandler_test.go:87"})
 }
 
 // This test incorporates an actual loop bug that I dropped on myself and
@@ -124,7 +123,6 @@ func TestGivenLoopingParserDefinition_ParserPanics(t *testing.T) {
 func TestGivenLoopingParserDefinition2_ParserPanics(t *testing.T) {
 	parser := parsekit.NewParser(func(p *parsekit.ParseAPI) {
 		for p.On(c.Max(5, a.AnyRune)).Accept() {
-			fmt.Printf("Cycle: %s\n", p.BufLiteral())
 			p.BufClear()
 		}
 		p.Stop()
@@ -133,5 +131,5 @@ func TestGivenLoopingParserDefinition2_ParserPanics(t *testing.T) {
 		func() { parser.Execute("This will end soon") },
 		"Loop detected in parser in git.makaay.nl/mauricem/go-parsekit_test." +
 			"TestGivenLoopingParserDefinition2_ParserPanics.func1 at " +
-			"/home/ubuntu/Projects/Parsekit/go-parsekit/parsehandler_test.go, line 126"})
+			"/home/ubuntu/Projects/Parsekit/go-parsekit/parsehandler_test.go:125"})
 }