diff --git a/phf/src/lib.rs b/phf/src/lib.rs
index d9c9a527..5fad1457 100644
--- a/phf/src/lib.rs
+++ b/phf/src/lib.rs
@@ -4,7 +4,7 @@
 //! `phf_macros` crate or via code generation in the `phf_codegen` crate. See
 //! the documentation of those crates for more details.
 #![doc(html_root_url="https://sfackler.github.io/rust-phf/doc")]
-#![feature(core, no_std)]
+#![feature(core, debug_builders)]
 #![warn(missing_docs)]
 
 extern crate phf_shared;
diff --git a/phf/src/map.rs b/phf/src/map.rs
index 2bdd8dbd..f8a50ee0 100644
--- a/phf/src/map.rs
+++ b/phf/src/map.rs
@@ -26,16 +26,11 @@ pub struct Map<K:'static, V:'static> {
 
 impl<K, V> fmt::Debug for Map<K, V> where K: fmt::Debug, V: fmt::Debug {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(fmt, "Map {{"));
-        let mut first = true;
-        for (k, v) in self.entries() {
-            if !first {
-                try!(write!(fmt, ", "));
-            }
-            try!(write!(fmt, "{:?}: {:?}", k, v));
-            first = false;
+        let mut builder = fmt.debug_map("Map");
+        for (k, v) in self {
+            builder = builder.entry(k, v);
         }
-        write!(fmt, "}}")
+        builder.finish()
     }
 }
 
diff --git a/phf/src/ordered_map.rs b/phf/src/ordered_map.rs
index 450923ef..4971fb77 100644
--- a/phf/src/ordered_map.rs
+++ b/phf/src/ordered_map.rs
@@ -32,16 +32,11 @@ pub struct OrderedMap<K:'static, V:'static> {
 
 impl<K, V> fmt::Debug for OrderedMap<K, V> where K: fmt::Debug, V: fmt::Debug {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(fmt, "OrderedMap {{"));
-        let mut first = true;
-        for (k, v) in self.entries() {
-            if !first {
-                try!(write!(fmt, ", "));
-            }
-            try!(write!(fmt, "{:?}: {:?}", k, v));
-            first = false;
+        let mut builder = fmt.debug_map("OrderedMap");
+        for (k, v) in self {
+            builder = builder.entry(k, v);
         }
-        write!(fmt, "}}")
+        builder.finish()
     }
 }
 
diff --git a/phf/src/ordered_set.rs b/phf/src/ordered_set.rs
index 0d538a2b..5bf74b12 100644
--- a/phf/src/ordered_set.rs
+++ b/phf/src/ordered_set.rs
@@ -23,16 +23,11 @@ pub struct OrderedSet<T:'static> {
 
 impl<T> fmt::Debug for OrderedSet<T> where T: fmt::Debug {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(fmt, "OrderedSet {{"));
-        let mut first = true;
-        for entry in self.iter() {
-            if !first {
-                try!(write!(fmt, ", "));
-            }
-            try!(write!(fmt, "{:?}", entry));
-            first = false;
+        let mut builder = fmt.debug_set("OrderedSet");
+        for entry in self {
+            builder = builder.entry(entry);
         }
-        write!(fmt, "}}")
+        builder.finish()
     }
 }
 
diff --git a/phf/src/set.rs b/phf/src/set.rs
index ecd8cda5..5c424582 100644
--- a/phf/src/set.rs
+++ b/phf/src/set.rs
@@ -22,16 +22,11 @@ pub struct Set<T:'static> {
 
 impl<T> fmt::Debug for Set<T> where T: fmt::Debug {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        try!(write!(fmt, "Set {{"));
-        let mut first = true;
-        for entry in self.iter() {
-            if !first {
-                try!(write!(fmt, ", "));
-            }
-            try!(write!(fmt, "{:?}", entry));
-            first = false;
+        let mut builder = fmt.debug_set("Set");
+        for entry in self {
+            builder = builder.entry(entry);
         }
-        write!(fmt, "}}")
+        builder.finish()
     }
 }
 
diff --git a/phf_codegen/src/lib.rs b/phf_codegen/src/lib.rs
index df9c09ab..843da7bf 100644
--- a/phf_codegen/src/lib.rs
+++ b/phf_codegen/src/lib.rs
@@ -55,8 +55,6 @@
 //! }
 //! ```
 #![doc(html_root_url="http://sfackler.github.io/rust-phf/doc")]
-#![feature(io)]
-
 extern crate phf_shared;
 extern crate phf_generator;
 
diff --git a/phf_codegen/test/build.rs b/phf_codegen/test/build.rs
index 77bbae1d..747c4ceb 100644
--- a/phf_codegen/test/build.rs
+++ b/phf_codegen/test/build.rs
@@ -1,5 +1,3 @@
-#![feature(io, path)]
-
 extern crate phf_codegen;
 
 use std::fs::File;
diff --git a/phf_macros/tests/test.rs b/phf_macros/tests/test.rs
index adba6bfb..2c3b641e 100644
--- a/phf_macros/tests/test.rs
+++ b/phf_macros/tests/test.rs
@@ -123,7 +123,7 @@ mod map {
     }
 
     #[test]
-    #[should_fail]
+    #[should_panic]
     fn test_index_fail() {
         static MAP: phf::Map<&'static str, isize> = phf_map!(
             "a" => 0,
@@ -378,7 +378,7 @@ mod ordered_map {
     }
 
     #[test]
-    #[should_fail]
+    #[should_panic]
     fn test_index_fail() {
         static MAP: phf::OrderedMap<&'static str, isize> = phf_ordered_map!(
             "a" => 0,