diff --git a/graphql/bool.go b/graphql/bool.go
index b175ca98628..f435e0c0988 100644
--- a/graphql/bool.go
+++ b/graphql/bool.go
@@ -7,13 +7,10 @@ import (
 )
 
 func MarshalBoolean(b bool) Marshaler {
-	return WriterFunc(func(w io.Writer) {
-		if b {
-			w.Write(trueLit)
-		} else {
-			w.Write(falseLit)
-		}
-	})
+	if b {
+		return WriterFunc(func(w io.Writer) { w.Write(trueLit) })
+	}
+	return WriterFunc(func(w io.Writer) { w.Write(falseLit) })
 }
 
 func UnmarshalBoolean(v interface{}) (bool, error) {
diff --git a/graphql/bool_test.go b/graphql/bool_test.go
new file mode 100644
index 00000000000..147237a1d63
--- /dev/null
+++ b/graphql/bool_test.go
@@ -0,0 +1,19 @@
+package graphql
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBoolean(t *testing.T) {
+	assert.Equal(t, "true", doBooleanMarshal(true))
+	assert.Equal(t, "false", doBooleanMarshal(false))
+}
+
+func doBooleanMarshal(b bool) string {
+	var buf bytes.Buffer
+	MarshalBoolean(b).MarshalGQL(&buf)
+	return buf.String()
+}