diff --git a/src/common.rs b/src/common.rs
index 927a4ba..d38e42b 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -61,6 +61,8 @@ pub enum Symbol {
     QuestionMark,
     /// \
     BackSlash,
+    /// `
+    BackTick
 }
 
 impl Display for Symbol {
@@ -95,6 +97,7 @@ impl Display for Symbol {
             Self::SingleQuote => write!(f, "'"),
             Self::QuestionMark => write!(f, "?"),
             Self::BackSlash => write!(f, "\\"),
+            Self::BackTick => write!(f, "`"),
         }
     }
 }
@@ -133,6 +136,7 @@ impl TryFrom<char> for Symbol {
             '\'' => Ok(Self::SingleQuote),
             '?' => Ok(Self::QuestionMark),
             '\\' => Ok(Self::BackSlash),
+            '`' => Ok(Self::BackTick),
             _ => Err("invalid symbol"),
         }
     }
diff --git a/src/lexer.rs b/src/lexer.rs
index c7e4901..d952464 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -133,7 +133,12 @@ impl<'a> Iterator for Lexer<'a> {
             '<' => symbol!(self, Lt),
             '>' => symbol!(self, Gt),
             '^' => symbol!(self, Xor),
+            '`' => symbol!(self, BackTick),
             '\0' => return None,
+            c if c.is_control() => {
+                self.buf.next();
+                TokenKind::Error("Expected expression.".into())
+            },
             _ => self.lex_ident(),
         };
         self.pos.next_char();
diff --git a/tests/error.rs b/tests/error.rs
index 3ce0e79..44df98b 100644
--- a/tests/error.rs
+++ b/tests/error.rs
@@ -5,5 +5,9 @@ mod macros;
 
 error!(
     nothing_after_decimal,
-    "a {\n  color: 1.;\n}\n", "Error: Expected digit."
+    "a {color: 1.;}", "Error: Expected digit."
+);
+error!(
+    ascii_control_character,
+    "a {color: ;}", "Error: Expected expression."
 );
diff --git a/tests/misc.rs b/tests/misc.rs
index 151e296..745a119 100644
--- a/tests/misc.rs
+++ b/tests/misc.rs
@@ -47,12 +47,22 @@ test!(
     "a {\n  color: red;\n}\n"
 );
 test!(
-    utf8_ident_before,
+    utf8_ident_before_len,
     "a {\n  color: length(😀red);\n}\n",
     "@charset \"UTF-8\";\na {\n  color: 1;\n}\n"
 );
 test!(
-    utf8_ident_after,
+    utf8_ident_before,
+    "a {\n  color: 😀red;\n}\n",
+    "@charset \"UTF-8\";\na {\n  color: 😀red;\n}\n"
+);
+test!(
+    utf8_ident_after_len,
     "a {\n  color: length(red😁)\n}\n",
     "@charset \"UTF-8\";\na {\n  color: 1;\n}\n"
 );
+test!(
+    utf8_ident_after,
+    "a {\n  color: red😁\n}\n",
+    "@charset \"UTF-8\";\na {\n  color: red😁;\n}\n"
+);