diff --git a/crates/macro/src/html_tree/html_tag/mod.rs b/crates/macro/src/html_tree/html_tag/mod.rs
index e74f04dd417..f1e020813a3 100644
--- a/crates/macro/src/html_tree/html_tag/mod.rs
+++ b/crates/macro/src/html_tree/html_tag/mod.rs
@@ -137,7 +137,7 @@ impl ToTokens for HtmlTag {
                 #vtag.add_classes(vec![#(&(#classes)),*]);
             },
             ClassesForm::Single(classes) => quote! {
-                #vtag.set_classes(&(#classes));
+                #vtag.set_classes(#classes);
             },
         });
 
diff --git a/src/services/resize.rs b/src/services/resize.rs
index 1af970ab962..c94d032cba6 100644
--- a/src/services/resize.rs
+++ b/src/services/resize.rs
@@ -1,8 +1,10 @@
 //! This module contains the implementation of a service that listens for browser window resize events.
 use stdweb::Value;
+use stdweb::{
+    js,
+    web::{window, Window},
+};
 use yew::callback::Callback;
-use stdweb::{js, web::{window, Window}};
-
 
 /// A service that fires events when the browser window resizes.
 #[derive(Default)]
diff --git a/src/virtual_dom/mod.rs b/src/virtual_dom/mod.rs
index 69c1b49c77d..ce461f536fe 100644
--- a/src/virtual_dom/mod.rs
+++ b/src/virtual_dom/mod.rs
@@ -6,10 +6,10 @@ pub mod vnode;
 pub mod vtag;
 pub mod vtext;
 
+use indexmap::set::IndexSet;
 use std::collections::HashMap;
 use std::fmt;
 use stdweb::web::{Element, EventListenerHandle, Node};
-use indexmap::set::IndexSet;
 
 pub use self::vcomp::VComp;
 pub use self::vlist::VList;
@@ -41,7 +41,62 @@ type Listeners<COMP> = Vec<Box<dyn Listener<COMP>>>;
 type Attributes = HashMap<String, String>;
 
 /// A set of classes.
-type Classes = IndexSet<String>;
+#[derive(Debug)]
+pub struct Classes {
+    set: IndexSet<String>,
+}
+
+impl Classes {
+    /// Creates empty set of classes.
+    pub fn new() -> Self {
+        Self {
+            set: IndexSet::new(),
+        }
+    }
+
+    /// Adds a class to a set.
+    pub fn push(&mut self, class: &str) {
+        self.set.insert(class.into());
+    }
+
+    /// Check the set contains a class.
+    pub fn contains(&self, class: &str) -> bool {
+        self.set.contains(class)
+    }
+}
+
+impl ToString for Classes {
+    fn to_string(&self) -> String {
+        let mut buf = String::new();
+        for class in &self.set {
+            buf.push_str(class);
+            buf.push(' ');
+        }
+        buf.pop();
+        buf
+    }
+}
+
+impl From<&str> for Classes {
+    fn from(t: &str) -> Self {
+        let set = t.split_whitespace().map(String::from).collect();
+        Self { set }
+    }
+}
+
+impl From<String> for Classes {
+    fn from(t: String) -> Self {
+        let set = t.split_whitespace().map(String::from).collect();
+        Self { set }
+    }
+}
+
+impl<T: AsRef<str>> From<Vec<T>> for Classes {
+    fn from(t: Vec<T>) -> Self {
+        let set = t.iter().map(|x| x.as_ref().to_string()).collect();
+        Self { set }
+    }
+}
 
 /// Patch for DOM node modification.
 enum Patch<ID, T> {
diff --git a/src/virtual_dom/vtag.rs b/src/virtual_dom/vtag.rs
index c78d9196aaa..021d359425e 100644
--- a/src/virtual_dom/vtag.rs
+++ b/src/virtual_dom/vtag.rs
@@ -96,7 +96,7 @@ impl<COMP: Component> VTag<COMP> {
     pub fn add_class(&mut self, class: &str) {
         let class = class.trim();
         if !class.is_empty() {
-            self.classes.insert(class.into());
+            self.classes.push(class);
         }
     }
 
@@ -107,7 +107,7 @@ impl<COMP: Component> VTag<COMP> {
         for class in classes {
             let class = class.trim();
             if !class.is_empty() {
-                self.classes.insert(class.into());
+                self.classes.push(class);
             }
         }
     }
@@ -115,8 +115,8 @@ impl<COMP: Component> VTag<COMP> {
     /// Add classes to this virtual node. Actually it will set by
     /// [Element.classList.add](https://developer.mozilla.org/en-US/docs/Web/API/Element/classList)
     /// call later.
-    pub fn set_classes(&mut self, classes: &str) {
-        self.classes = classes.split_whitespace().map(String::from).collect();
+    pub fn set_classes(&mut self, classes: impl Into<Classes>) {
+        self.classes = classes.into();
     }
 
     /// Sets `value` for an
@@ -187,18 +187,21 @@ impl<COMP: Component> VTag<COMP> {
             // Only change what is necessary.
             let to_add = self
                 .classes
-                .difference(&ancestor.classes)
+                .set
+                .difference(&ancestor.classes.set)
                 .map(|class| Patch::Add(class.to_owned(), ()));
             changes.extend(to_add);
             let to_remove = ancestor
                 .classes
-                .difference(&self.classes)
+                .set
+                .difference(&self.classes.set)
                 .map(|class| Patch::Remove(class.to_owned()));
             changes.extend(to_remove);
         } else {
             // Add everything
             let to_add = self
                 .classes
+                .set
                 .iter()
                 .map(|class| Patch::Add(class.to_owned(), ()));
             changes.extend(to_add);
@@ -558,7 +561,7 @@ impl<COMP: Component> PartialEq for VTag<COMP> {
             return false;
         }
 
-        if self.classes.iter().ne(other.classes.iter()) {
+        if self.classes.set.iter().ne(other.classes.set.iter()) {
             return false;
         }
 
diff --git a/tests/vtag_test.rs b/tests/vtag_test.rs
index 211b11bad3f..8a55ea560c7 100644
--- a/tests/vtag_test.rs
+++ b/tests/vtag_test.rs
@@ -216,6 +216,24 @@ fn supports_multiple_classes_string() {
     }
 }
 
+#[test]
+fn supports_multiple_classes_vec() {
+    let mut classes = vec!["class-1"];
+    classes.push("class-2");
+    let a: VNode<Comp> = html! {
+        <div class=classes></div>
+    };
+
+    if let VNode::VTag(vtag) = a {
+        println!("{:?}", vtag.classes);
+        assert!(vtag.classes.contains("class-1"));
+        assert!(vtag.classes.contains("class-2"));
+        assert!(!vtag.classes.contains("class-3"));
+    } else {
+        panic!("vtag expected");
+    }
+}
+
 fn assert_vtag(node: &mut VNode<Comp>) -> &mut VTag<Comp> {
     if let VNode::VTag(vtag) = node {
         return vtag;
@@ -261,16 +279,9 @@ fn keeps_order_of_classes() {
         <div class="class-1 class-2   class-3",></div>
     };
 
-    if let VNode::VTag(mut vtag) = a {
+    if let VNode::VTag(vtag) = a {
         println!("{:?}", vtag.classes);
-        assert_eq!(
-            vtag.classes.drain(..).collect::<Vec<String>>(),
-            vec![
-                String::from("class-1"),
-                String::from("class-2"),
-                String::from("class-3")
-            ]
-        )
+        assert_eq!(vtag.classes.to_string(), "class-1 class-2 class-3");
     }
 }