diff --git a/interpreter/interpretable.go b/interpreter/interpretable.go
index 74aef257..f9724d46 100644
--- a/interpreter/interpretable.go
+++ b/interpreter/interpretable.go
@@ -110,10 +110,11 @@ type InterpretableConstructor interface {
 // Core Interpretable implementations used during the program planning phase.
 
 type evalTestOnly struct {
-	id    int64
-	attr  InterpretableAttribute
-	qual  Qualifier
-	field types.String
+	id           int64
+	attr         InterpretableAttribute
+	qual         Qualifier
+	field        types.String
+	isProtoField bool
 }
 
 // ID implements the Interpretable interface method.
diff --git a/interpreter/planner.go b/interpreter/planner.go
index 620f9aac..165a388b 100644
--- a/interpreter/planner.go
+++ b/interpreter/planner.go
@@ -220,11 +220,19 @@ func (p *planner) planSelect(expr *exprpb.Expr) (Interpretable, error) {
 
 	// Return the test only eval expression.
 	if sel.GetTestOnly() {
+		isProtoField := false
+		if opType.GetMessageType() != "" {
+			ft, found := p.provider.FindFieldType(opType.GetMessageType(), sel.GetField())
+			if found && ft.IsSet != nil && ft.GetFrom != nil {
+				isProtoField = true
+			}
+		}
 		return &evalTestOnly{
-			id:    expr.GetId(),
-			field: types.String(sel.GetField()),
-			attr:  attr,
-			qual:  qual,
+			id:           expr.GetId(),
+			field:        types.String(sel.GetField()),
+			attr:         attr,
+			qual:         qual,
+			isProtoField: isProtoField,
 		}, nil
 	}
 
diff --git a/interpreter/runtimecost.go b/interpreter/runtimecost.go
index 42e64a44..33a4ea56 100644
--- a/interpreter/runtimecost.go
+++ b/interpreter/runtimecost.go
@@ -38,6 +38,12 @@ type ActualCostEstimator interface {
 func CostObserver(tracker *CostTracker) EvalObserver {
 	observer := func(id int64, programStep any, val ref.Val) {
 		switch t := programStep.(type) {
+		case *evalTestOnly:
+			// Protobuf has() checks do not incur runtime cost due to not using Eval()
+			// in older versions of CEL; this keeps the runtime cost behavior consistent
+			if !t.isProtoField {
+				tracker.cost++
+			}
 		case ConstantQualifier:
 			// TODO: Push identifiers on to the stack before observing constant qualifiers that apply to them
 			// and enable the below pop. Once enabled this can case can be collapsed into the Qualifier case.