diff --git a/src/common.rs b/src/common.rs
index b343d0b..2e85755 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -76,7 +76,7 @@ impl Display for Symbol {
             Self::At => write!(f, "@"),
             Self::Dollar => write!(f, "$"),
             Self::OpenParen => write!(f, "("),
-            Self::CloseParen => write!(f, "),"),
+            Self::CloseParen => write!(f, ")"),
             Self::OpenCurlyBrace => write!(f, "{{"),
             Self::CloseCurlyBrace => write!(f, "}}"),
             Self::OpenSquareBrace => write!(f, "["),
diff --git a/src/value/number.rs b/src/value/number.rs
index 3921b62..95820a1 100644
--- a/src/value/number.rs
+++ b/src/value/number.rs
@@ -81,7 +81,7 @@ impl Display for Number {
         let mut frac = self.val.fract();
         if frac != BigRational::from_integer(BigInt::from(0)) {
             f.write_char('.')?;
-            for _ in 0..(PRECISION-1) {
+            for _ in 0..(PRECISION - 1) {
                 frac *= BigRational::from_integer(BigInt::from(10));
                 write!(f, "{}", frac.to_integer())?;
                 frac = frac.fract();
diff --git a/src/value/ops.rs b/src/value/ops.rs
index da214b4..e9284ad 100644
--- a/src/value/ops.rs
+++ b/src/value/ops.rs
@@ -22,6 +22,13 @@ impl Add for Value {
             },
             Self::Dimension(num, unit) => match other {
                 Self::Dimension(num2, unit2) => Value::Dimension(num + num2, unit),
+                Self::Ident(s, q) => {
+                    let quotes = match q {
+                        QuoteKind::Double | QuoteKind::Single => QuoteKind::Double,
+                        QuoteKind::None => QuoteKind::None,
+                    };
+                    Value::Ident(format!("{}{}{}", num, unit, s), quotes)
+                }
                 _ => todo!(),
             },
             // Self::List(..) => todo!(),
diff --git a/src/value/parse.rs b/src/value/parse.rs
index 395e7ae..1cd879b 100644
--- a/src/value/parse.rs
+++ b/src/value/parse.rs
@@ -219,15 +219,47 @@ impl Value {
                         ..
                     }) => {
                         toks.next();
-                        let args = eat_call_args(toks, scope);
                         let func = match scope.get_fn(&s) {
                             Ok(f) => f,
                             Err(_) => match GLOBAL_FUNCTIONS.get(&s) {
-                                Some(f) => return f(&args, scope),
-                                None => todo!("called undefined function"),
+                                Some(f) => return f(&eat_call_args(toks, scope), scope),
+                                None => {
+                                    s.push('(');
+                                    let mut unclosed_parens = 0;
+                                    while let Some(t) = toks.next() {
+                                        match &t.kind {
+                                            TokenKind::Symbol(Symbol::OpenParen) => {
+                                                unclosed_parens += 1;
+                                            }
+                                            TokenKind::Interpolation => s.push_str(
+                                                &parse_interpolation(toks, scope)
+                                                    .iter()
+                                                    .map(|x| x.kind.to_string())
+                                                    .collect::<String>(),
+                                            ),
+                                            TokenKind::Variable(v) => s.push_str(
+                                                &scope
+                                                    .get_var(v)
+                                                    .expect("expected variable to exist")
+                                                    .to_string(),
+                                            ),
+                                            TokenKind::Symbol(Symbol::CloseParen) => {
+                                                if unclosed_parens <= 1 {
+                                                    s.push(')');
+                                                    break;
+                                                } else {
+                                                    unclosed_parens -= 1;
+                                                }
+                                            }
+                                            _ => {}
+                                        }
+                                        s.push_str(&t.kind.to_string());
+                                    }
+                                    return Some(Value::Ident(s, QuoteKind::None));
+                                }
                             },
                         };
-                        Some(func.clone().args(&args).call())
+                        Some(func.clone().args(&eat_call_args(toks, scope)).call())
                     }
                     _ => {
                         if let Ok(c) = crate::color::ColorName::try_from(s.as_ref()) {
diff --git a/tests/values.rs b/tests/values.rs
index a16dca6..aace14c 100644
--- a/tests/values.rs
+++ b/tests/values.rs
@@ -294,3 +294,12 @@ test!(
     "a {\n  color: 'foo' - 1px;\n}\n",
     "a {\n  color: \"foo\"-1px;\n}\n"
 );
+test!(
+    undefined_function_call_is_ident,
+    "a {\n  color: foo();\n}\n"
+);
+test!(
+    undefined_function_call_is_ident_adds,
+    "a {\n  color: 1 + foo();\n}\n",
+    "a {\n  color: 1foo();\n}\n"
+);