diff --git a/mux.go b/mux.go
index e22dcac..caa8ad5 100644
--- a/mux.go
+++ b/mux.go
@@ -146,6 +146,13 @@ func (r *Router) getRegexpGroup() *routeRegexpGroup {
 	return nil
 }
 
+func (r *Router) buildVars(m map[string]string) map[string]string {
+	if r.parent != nil {
+		m = r.parent.buildVars(m)
+	}
+	return m
+}
+
 // ----------------------------------------------------------------------------
 // Route factories
 // ----------------------------------------------------------------------------
diff --git a/mux_test.go b/mux_test.go
index bd76a01..b163639 100644
--- a/mux_test.go
+++ b/mux_test.go
@@ -514,6 +514,7 @@ func TestMatcherFunc(t *testing.T) {
 func TestBuildVarsFunc(t *testing.T) {
 	tests := []routeTest{
 		{
+			title: "BuildVarsFunc set on route",
 			route: new(Route).Path(`/111/{v1:\d}{v2:.*}`).BuildVarsFunc(func(vars map[string]string) map[string]string {
 				vars["v1"] = "3"
 				vars["v2"] = "a"
@@ -523,6 +524,19 @@ func TestBuildVarsFunc(t *testing.T) {
 			path:        "/111/3a",
 			shouldMatch: true,
 		},
+		{
+			title: "BuildVarsFunc set on route and parent route",
+			route: new(Route).PathPrefix(`/{v1:\d}`).BuildVarsFunc(func(vars map[string]string) map[string]string {
+				vars["v1"] = "2"
+				return vars
+			}).Subrouter().Path(`/{v2:\w}`).BuildVarsFunc(func(vars map[string]string) map[string]string {
+				vars["v2"] = "b"
+				return vars
+			}),
+			request:     newRequest("GET", "http://localhost/1/a"),
+			path:        "/2/b",
+			shouldMatch: true,
+		},
 	}
 
 	for _, test := range tests {
diff --git a/route.go b/route.go
index e79afa7..b2900de 100644
--- a/route.go
+++ b/route.go
@@ -413,7 +413,7 @@ func (r *Route) URL(pairs ...string) (*url.URL, error) {
 	if r.regexp == nil {
 		return nil, errors.New("mux: route doesn't have a host or path")
 	}
-	values, err := r.buildVars(pairs...)
+	values, err := r.prepareVars(pairs...)
 	if err != nil {
 		return nil, err
 	}
@@ -447,7 +447,7 @@ func (r *Route) URLHost(pairs ...string) (*url.URL, error) {
 	if r.regexp == nil || r.regexp.host == nil {
 		return nil, errors.New("mux: route doesn't have a host")
 	}
-	values, err := r.buildVars(pairs...)
+	values, err := r.prepareVars(pairs...)
 	if err != nil {
 		return nil, err
 	}
@@ -471,7 +471,7 @@ func (r *Route) URLPath(pairs ...string) (*url.URL, error) {
 	if r.regexp == nil || r.regexp.path == nil {
 		return nil, errors.New("mux: route doesn't have a path")
 	}
-	values, err := r.buildVars(pairs...)
+	values, err := r.prepareVars(pairs...)
 	if err != nil {
 		return nil, err
 	}
@@ -484,17 +484,24 @@ func (r *Route) URLPath(pairs ...string) (*url.URL, error) {
 	}, nil
 }
 
-// buildVars converts the route variable pairs into a map. If the route has a
+// prepareVars converts the route variable pairs into a map. If the route has a
 // BuildVarsFunc, it is invoked.
-func (r *Route) buildVars(pairs ...string) (map[string]string, error) {
+func (r *Route) prepareVars(pairs ...string) (map[string]string, error) {
 	m, err := mapFromPairs(pairs...)
 	if err != nil {
 		return nil, err
 	}
+	return r.buildVars(m), nil
+}
+
+func (r *Route) buildVars(m map[string]string) map[string]string {
+	if r.parent != nil {
+		m = r.parent.buildVars(m)
+	}
 	if r.buildVarsFunc != nil {
 		m = r.buildVarsFunc(m)
 	}
-	return m, nil
+	return m
 }
 
 // ----------------------------------------------------------------------------
@@ -505,6 +512,7 @@ func (r *Route) buildVars(pairs ...string) (map[string]string, error) {
 type parentRoute interface {
 	getNamedRoutes() map[string]*Route
 	getRegexpGroup() *routeRegexpGroup
+	buildVars(map[string]string) map[string]string
 }
 
 // getNamedRoutes returns the map where named routes are registered.