diff --git a/assets/fingerprint.go b/assets/fingerprint.go
index a6e77c4..3f5a7f8 100644
--- a/assets/fingerprint.go
+++ b/assets/fingerprint.go
@@ -11,15 +11,16 @@ import (
 
 // PathFor returns the fingerprinted path for a given
 // file. If the path passed contains the hash it will
-// return the same path.
+// return the same path only in GO_ENV=development
 
 // filename to open should be the file without the prefix
 // filename for the map should be the file without the prefix
 // filename returned should be the file with the prefix
 func (m *manager) PathFor(name string) (string, error) {
 	normalized := m.normalize(name)
-	if hashed, ok := m.fileToHash[normalized]; ok {
-		return path.Join(m.servingPath, hashed), nil
+
+	if hashed, ok := m.fileToHash[normalized]; ok && os.Getenv("GO_ENV") != "development" {
+		return path.Join("/", m.servingPath, hashed), nil
 	}
 
 	// Compute the hash of the file
@@ -38,6 +39,12 @@ func (m *manager) PathFor(name string) (string, error) {
 
 	m.fmut.Lock()
 	defer m.fmut.Unlock()
+
+	// Delete previous asset hash from map
+	if old, exists := m.fileToHash[normalized]; exists && old != filename {
+		delete(m.HashToFile, old)
+	}
+
 	m.fileToHash[normalized] = filename
 	m.HashToFile[filename] = normalized
 
diff --git a/assets/fingerprint_test.go b/assets/fingerprint_test.go
index 357aa21..05e8903 100644
--- a/assets/fingerprint_test.go
+++ b/assets/fingerprint_test.go
@@ -9,7 +9,7 @@ import (
 )
 
 func TestFingerprint(t *testing.T) {
-	assetsPath := "/files/"
+	assetsPath := "/files"
 	m := assets.NewManager(fstest.MapFS{
 		"main.js":        {Data: []byte("AAA")},
 		"other/main.js":  {Data: []byte("AAA")},
@@ -125,6 +125,45 @@ func TestFingerprint(t *testing.T) {
 		}
 	})
 
+	t.Run("HandlerPattern", func(t *testing.T) {
+		cases := []struct {
+			pattern  string
+			expected string
+		}{
+			{"/", ""},
+			{"/", ""},
+
+			{"files", "/files/"},
+			{"/files/", "/files/"},
+			{"files/", "/files/"},
+			{"/files/", "/files/"},
+
+			{"files/path", "/files/path/"},
+			{"/files/path", "/files/path/"},
+			{"files/path/", "/files/path/"},
+			{"/files/path/", "/files/path/"},
+		}
+
+		for _, c := range cases {
+			m := assets.NewManager(fstest.MapFS{}, c.pattern)
+			if m.HandlerPattern() != c.expected {
+				t.Errorf("Expected %q to equal %q", m.HandlerPattern(), c.expected)
+			}
+		}
+	})
+
+	t.Run("HandlerPattern with root serving path", func(t *testing.T) {
+		m := assets.NewManager(fstest.MapFS{}, "/")
+		if m.HandlerPattern() == "/" {
+			t.Errorf("Expected empty string, got %s", m.HandlerPattern())
+		}
+
+		m = assets.NewManager(fstest.MapFS{}, "public")
+		if m.HandlerPattern() != "/public/" {
+			t.Errorf("Expected '/public/', got %s", m.HandlerPattern())
+		}
+	})
+
 	t.Run("PathFor normalize file path", func(t *testing.T) {
 		cases := []struct {
 			servingPath string
@@ -186,4 +225,52 @@ func TestFingerprint(t *testing.T) {
 			}
 		}
 	})
+
+	t.Run("recalculate hashed files only un development", func(t *testing.T) {
+		fsMap := fstest.MapFS{
+			"main.js": {Data: []byte("AAA")},
+		}
+
+		m := assets.NewManager(fsMap, assetsPath)
+
+		t.Run("in development mode should recalculate the asset hash", func(t *testing.T) {
+			t.Setenv("GO_ENV", "development")
+
+			a, err := m.PathFor("main.js")
+			if err != nil {
+				t.Errorf("Expected nil, got %s", err)
+			}
+
+			fsMap["main.js"] = &fstest.MapFile{Data: []byte("BBB")}
+
+			b, err := m.PathFor("main.js")
+			if err != nil {
+				t.Errorf("Expected nil, got %s", err)
+			}
+
+			if a == b {
+				t.Errorf("Expected %s to not equal %s", a, b)
+			}
+		})
+
+		t.Run("in other env should not recalculate the asset hash", func(t *testing.T) {
+			t.Setenv("GO_ENV", "production")
+
+			a, err := m.PathFor("main.js")
+			if err != nil {
+				t.Errorf("Expected nil, got %s", err)
+			}
+
+			fsMap["main.js"] = &fstest.MapFile{Data: []byte("CCC")}
+
+			b, err := m.PathFor("main.js")
+			if err != nil {
+				t.Errorf("Expected nil, got %s", err)
+			}
+
+			if a != b {
+				t.Errorf("Expected %s to equal %s", a, b)
+			}
+		})
+	})
 }
diff --git a/assets/manager.go b/assets/manager.go
index 716dc06..108e181 100644
--- a/assets/manager.go
+++ b/assets/manager.go
@@ -24,12 +24,11 @@ func NewManager(embedded fs.FS, servingPath string) *manager {
 		servingPath = "/"
 	}
 
-	if !strings.HasPrefix(servingPath, "/") {
-		servingPath = "/" + servingPath
-	}
-
-	if !strings.HasSuffix(servingPath, "/") {
-		servingPath += "/"
+	servingPath = strings.Trim(servingPath, "/")
+	if servingPath == "" {
+		servingPath = "/"
+	} else {
+		servingPath = "/" + servingPath + "/"
 	}
 
 	return &manager{