diff --git a/src/datetime.rs b/src/datetime.rs
index e3c3670..6f6f71d 100644
--- a/src/datetime.rs
+++ b/src/datetime.rs
@@ -418,9 +418,9 @@ fn test_encodable_json<FUTC, FFixed, E>(to_string_utc: FUTC, to_string_fixed: FF
 fn test_decodable_json<FUTC, FFixed, FLocal, E>(utc_from_str: FUTC,
                                                      fixed_from_str: FFixed,
                                                      local_from_str: FLocal)
-    where FUTC: for<'de> Fn(&'de str) -> Result<DateTime<UTC>, E>,
-          FFixed: for<'de> Fn(&'de str) -> Result<DateTime<FixedOffset>, E>,
-          FLocal: for<'de> Fn(&'de str) -> Result<DateTime<Local>, E>,
+    where FUTC: Fn(&str) -> Result<DateTime<UTC>, E>,
+          FFixed: Fn(&str) -> Result<DateTime<FixedOffset>, E>,
+          FLocal: Fn(&str) -> Result<DateTime<Local>, E>,
           E: ::std::fmt::Debug
 {
     // should check against the offset as well (the normal DateTime comparison will ignore them)
diff --git a/src/naive/date.rs b/src/naive/date.rs
index 79cb3f2..b302c37 100644
--- a/src/naive/date.rs
+++ b/src/naive/date.rs
@@ -1495,7 +1495,7 @@ fn test_encodable_json<F, E>(to_string: F)
 
 #[cfg(all(test, any(feature = "rustc-serialize", feature = "serde")))]
 fn test_decodable_json<F, E>(from_str: F)
-    where F: for<'de> Fn(&'de str) -> Result<NaiveDate, E>, E: ::std::fmt::Debug
+    where F: Fn(&str) -> Result<NaiveDate, E>, E: ::std::fmt::Debug
 {
     use std::{i32, i64};
 
diff --git a/src/naive/datetime.rs b/src/naive/datetime.rs
index f68210e..0271218 100644
--- a/src/naive/datetime.rs
+++ b/src/naive/datetime.rs
@@ -1371,7 +1371,7 @@ fn test_encodable_json<F, E>(to_string: F)
 
 #[cfg(all(test, any(feature = "rustc-serialize", feature = "serde")))]
 fn test_decodable_json<F, E>(from_str: F)
-    where F: for<'de> Fn(&'de str) -> Result<NaiveDateTime, E>, E: ::std::fmt::Debug
+    where F: Fn(&str) -> Result<NaiveDateTime, E>, E: ::std::fmt::Debug
 {
     use naive::date;
 
diff --git a/src/naive/time.rs b/src/naive/time.rs
index 7f0e7d3..9157e9a 100644
--- a/src/naive/time.rs
+++ b/src/naive/time.rs
@@ -1261,7 +1261,7 @@ fn test_encodable_json<F, E>(to_string: F)
 
 #[cfg(all(test, any(feature = "rustc-serialize", feature = "serde")))]
 fn test_decodable_json<F, E>(from_str: F)
-    where F: for<'de> Fn(&'de str) -> Result<NaiveTime, E>, E: ::std::fmt::Debug
+    where F: Fn(&str) -> Result<NaiveTime, E>, E: ::std::fmt::Debug
 {
     assert_eq!(from_str(r#""00:00:00""#).ok(),
                Some(NaiveTime::from_hms(0, 0, 0)));