diff --git a/src/parse/value/css_function.rs b/src/parse/value/css_function.rs
index b900685..c20b0c3 100644
--- a/src/parse/value/css_function.rs
+++ b/src/parse/value/css_function.rs
@@ -64,7 +64,12 @@ impl<'a> Parser<'a> {
 
     pub(super) fn parse_progid(&mut self) -> SassResult<String> {
         let mut string = String::new();
-        let mut span = self.toks.peek().unwrap().pos();
+        let mut span = match self.toks.peek() {
+            Some(token) => token.pos(),
+            None => {
+                return Err(("expected \"(\".", self.span_before).into());
+            }
+        };
         while let Some(tok) = self.toks.next() {
             span = span.merge(tok.pos());
             match tok.kind {
diff --git a/tests/special-functions.rs b/tests/special-functions.rs
index b3ed40b..6db0887 100644
--- a/tests/special-functions.rs
+++ b/tests/special-functions.rs
@@ -202,3 +202,7 @@ test!(
     "a {\n  color: PrOgId:foo(fff);\n}\n",
     "a {\n  color: progid:foo(fff);\n}\n"
 );
+error!(
+    progid_nothing_after,
+    "a { color: progid:", "Error: expected \"(\"."
+);