diff --git a/parser.go b/parser.go
index 7eb381e2..49698a61 100644
--- a/parser.go
+++ b/parser.go
@@ -34,14 +34,12 @@ func buildURL(baseURL, stepURL string) string {
 
 func parseHeaders(rawHeaders map[string]string, variablesMapping map[string]interface{}) map[string]string {
 	parsedHeaders := make(map[string]string)
-	for k, v := range rawHeaders {
-		parsedValue := parseString(v, variablesMapping)
-		if value, ok := parsedValue.(string); ok {
+	headers := parseData(rawHeaders, variablesMapping).(map[string]interface{})
+	for k, v := range headers {
+		if value, ok := v.(string); ok {
 			parsedHeaders[k] = value
 		} else {
-			// parsed value is not string, e.g. int, float, etc.
-			// convert to string
-			parsedHeaders[k] = fmt.Sprintf("%v", parsedValue)
+			parsedHeaders[k] = fmt.Sprintf("%v", v)
 		}
 	}
 	return parsedHeaders
diff --git a/parser_test.go b/parser_test.go
index b6e1110c..7f6618b0 100644
--- a/parser_test.go
+++ b/parser_test.go
@@ -143,9 +143,9 @@ func TestParseDataMapWithVariables(t *testing.T) {
 	}{
 		{map[string]interface{}{"key": "$var1"}, map[string]interface{}{"key": "foo1"}},
 		{map[string]interface{}{"foo1": "$val1", "foo2": "bar2"}, map[string]interface{}{"foo1": 200, "foo2": "bar2"}},
-		// parse map key
+		// parse map key, key is string
 		{map[string]interface{}{"$var1": "$val1"}, map[string]interface{}{"foo1": 200}},
-		// map key is int
+		// parse map key, key is int
 		{map[string]interface{}{"$var2": "$val1"}, map[string]interface{}{"123": 200}},
 	}
 
@@ -155,3 +155,32 @@ func TestParseDataMapWithVariables(t *testing.T) {
 		}
 	}
 }
+
+func TestParseHeaders(t *testing.T) {
+	variablesMapping := map[string]interface{}{
+		"var1": "foo1",
+		"val1": 200,
+		"var2": 123, // key is int
+		"val2": nil, // value is nil
+	}
+
+	testData := []struct {
+		rawHeaders    map[string]string
+		expectHeaders map[string]string
+	}{
+		{map[string]string{"key": "$var1"}, map[string]string{"key": "foo1"}},
+		{map[string]string{"foo1": "$val1", "foo2": "bar2"}, map[string]string{"foo1": "200", "foo2": "bar2"}},
+		// parse map key, key is string
+		{map[string]string{"$var1": "$val1"}, map[string]string{"foo1": "200"}},
+		// parse map key, key is int
+		{map[string]string{"$var2": "$val1"}, map[string]string{"123": "200"}},
+		// parse map key & value, key is int, value is nil
+		{map[string]string{"$var2": "$val2"}, map[string]string{"123": "<nil>"}},
+	}
+
+	for _, data := range testData {
+		if !assert.Equal(t, data.expectHeaders, parseHeaders(data.rawHeaders, variablesMapping)) {
+			t.Fail()
+		}
+	}
+}