diff --git a/src/date.rs b/src/date.rs
index 5cdb691..aa4e710 100644
--- a/src/date.rs
+++ b/src/date.rs
@@ -22,7 +22,7 @@ impl Display for Date {
 }
 
 pub fn parse(paren: Group, iter: Iter) -> Result<Date> {
-    try_parse(iter).map_err(|_| {
+    try_parse(iter).map_err(|()| {
         let msg = format!("expected nightly date, like {}", time::today());
         Error::group(paren, msg)
     })
diff --git a/src/release.rs b/src/release.rs
index 3f421c6..c8c0219 100644
--- a/src/release.rs
+++ b/src/release.rs
@@ -10,7 +10,7 @@ pub struct Release {
 }
 
 pub fn parse(paren: Group, iter: Iter) -> Result<Release> {
-    try_parse(iter).map_err(|_| Error::group(paren, "expected rustc release number, like 1.31"))
+    try_parse(iter).map_err(|()| Error::group(paren, "expected rustc release number, like 1.31"))
 }
 
 fn try_parse(iter: Iter) -> Result<Release, ()> {