diff --git a/src/syn/lexer.rs b/src/syn/lexer.rs
index a117275..6112128 100644
--- a/src/syn/lexer.rs
+++ b/src/syn/lexer.rs
@@ -7,12 +7,11 @@ lazy_static! {
         r#"^(
             (?P<float>[-+]?[0-9]+\.[0-9]+([eE][+\-][0-9]+)?)
         |   (?P<int>[-+]?[0-9]+)
-        |   (?P<assign>=[a-zA-Z_?\-*+/.'@$%^&|][0-9a-zA-Z_?\-*+/=.'@$%^&|]*)
+        |   (?P<assign>:[a-zA-Z_?\-*+/=.'@$%^&|][0-9a-zA-Z_?\-*+/=.'@$%^&|]*)
         |   (?P<meta>%[a-zA-Z0-9\-_]+)
         |   (?P<word>[a-zA-Z_?\-*+/=.'@$%^&|][0-9a-zA-Z_?\-*+/=.'@$%^&|]*)
         |   (?P<lquote>\[)
         |   (?P<rquote>\])
-        |   (?P<colon>:)
         |   (?P<apply>!)
         |   (?P<str>"([^"\\]|\\["'\\ntrb])*")
         )"#
@@ -104,8 +103,6 @@ impl<'t> Lexer<'t> {
                 self.make_token(Token::LQuote)
             } else if let Some(_) = cap.name("rquote") {
                 self.make_token(Token::RQuote)
-            } else if let Some(_) = cap.name("colon") {
-                self.make_token(Token::Colon)
             } else if let Some(_) = cap.name("apply") {
                 self.make_token(Token::Apply)
             } else {
@@ -168,7 +165,7 @@ mod test {
 
     #[test]
     fn test_word() {
-        let mut lexer = Lexer::new(r"a b c d foo bar baz");
+        let mut lexer = Lexer::new(r"a b c d foo bar baz = == === =a ==a ===a");
         assert_token!(lexer, Token::Word, "a");
         assert_token!(lexer, Token::Word, "b");
         assert_token!(lexer, Token::Word, "c");
@@ -178,21 +175,24 @@ mod test {
         assert_token!(lexer, Token::Word, "bar");
         assert_token!(lexer, Token::Word, "baz");
 
+        assert_token!(lexer, Token::Word, "=");
+        assert_token!(lexer, Token::Word, "==");
+        assert_token!(lexer, Token::Word, "===");
+        assert_token!(lexer, Token::Word, "=a");
+        assert_token!(lexer, Token::Word, "==a");
+        assert_token!(lexer, Token::Word, "===a");
+
         assert!(lexer.is_eof());
     }
 
     #[test]
     fn test_assign() {
-        let mut lexer = Lexer::new(r"= == === =a ==a ===a = a");
-        assert_token!(lexer, Token::Word, "=");
-        assert_token!(lexer, Token::Word, "==");
-        assert_token!(lexer, Token::Word, "===");
-        assert_token!(lexer, Token::Assign, "=a");
-        assert_token!(lexer, Token::Word, "==a");
-        assert_token!(lexer, Token::Word, "===a");
-        assert_token!(lexer, Token::Word, "=");
-        assert_token!(lexer, Token::Word, "a");
-
+        let mut lexer = Lexer::new(r":a := :foo :foo-bar :foo-bar-baz");
+        assert_token!(lexer, Token::Assign, ":a");
+        assert_token!(lexer, Token::Assign, ":=");
+        assert_token!(lexer, Token::Assign, ":foo");
+        assert_token!(lexer, Token::Assign, ":foo-bar");
+        assert_token!(lexer, Token::Assign, ":foo-bar-baz");
         assert!(lexer.is_eof());
     }
 
@@ -240,22 +240,4 @@ mod test {
         assert_token!(lexer, Token::LQuote);
         assert!(lexer.is_eof());
     }
-
-    #[test]
-    fn test_colon() {
-        let mut lexer = Lexer::new(": :: ::: :::: some-name:");
-        assert_token!(lexer, Token::Colon);
-        assert_token!(lexer, Token::Colon);
-        assert_token!(lexer, Token::Colon);
-        assert_token!(lexer, Token::Colon);
-        assert_token!(lexer, Token::Colon);
-        assert_token!(lexer, Token::Colon);
-        assert_token!(lexer, Token::Colon);
-        assert_token!(lexer, Token::Colon);
-        assert_token!(lexer, Token::Colon);
-        assert_token!(lexer, Token::Colon);
-        assert_token!(lexer, Token::Word);
-        assert_token!(lexer, Token::Colon);
-        assert!(lexer.is_eof());
-    }
 }
diff --git a/src/syn/token.rs b/src/syn/token.rs
index 60508ae..b9df218 100644
--- a/src/syn/token.rs
+++ b/src/syn/token.rs
@@ -24,9 +24,6 @@ pub enum Token {
     /// Quote end.
     RQuote,
 
-    /// Colon.
-    Colon,
-
     /// Apply.
     Apply,
 
@@ -45,7 +42,6 @@ impl Token {
             Str => "str",
             LQuote => "quote begin",
             RQuote => "quote end",
-            Colon => "colon",
             Apply => "apply",
             Meta => "meta",
         }