diff --git a/miniconf/Cargo.toml b/miniconf/Cargo.toml
index c6a9edb5..d66e081c 100644
--- a/miniconf/Cargo.toml
+++ b/miniconf/Cargo.toml
@@ -51,7 +51,7 @@ required-features = ["json-core", "derive"]
 
 [[test]]
 name = "basic"
-required-features = ["derive"]
+required-features = ["json-core", "derive"]
 
 [[test]]
 name = "generics"
@@ -89,9 +89,14 @@ required-features = ["json-core", "derive"]
 name = "flatten"
 required-features = ["json-core", "derive"]
 
+[[test]]
+name = "compiletest"
+required-features = ["derive"]
+
 [[example]]
 name = "common"
 crate-type = ["lib"]
+required-features = ["derive"]
 
 [[example]]
 name = "cli"
diff --git a/miniconf/src/impls.rs b/miniconf/src/impls.rs
index b2d66ad3..b266810c 100644
--- a/miniconf/src/impls.rs
+++ b/miniconf/src/impls.rs
@@ -758,24 +758,6 @@ impl<T: TreeAny> TreeAny for Cell<T> {
     }
 }
 
-impl<T: TreeAny> TreeAny for &Cell<T> {
-    #[inline]
-    fn ref_any_by_key<K>(&self, _keys: K) -> Result<&dyn Any, Traversal>
-    where
-        K: Keys,
-    {
-        Err(Traversal::Access(0, "Can't leak out of Cell"))
-    }
-
-    #[inline]
-    fn mut_any_by_key<K>(&mut self, _keys: K) -> Result<&mut dyn Any, Traversal>
-    where
-        K: Keys,
-    {
-        Err(Traversal::Access(0, "Can't leak out of Cell"))
-    }
-}
-
 /////////////////////////////////////////////////////////////////////////////////////////
 
 impl<T: TreeKey> TreeKey for RefCell<T> {
@@ -807,27 +789,27 @@ impl<T: TreeSerialize> TreeSerialize for RefCell<T> {
     }
 }
 
-impl<'de, T: TreeDeserialize<'de>> TreeDeserialize<'de> for &RefCell<T> {
+impl<'de, T: TreeDeserialize<'de>> TreeDeserialize<'de> for RefCell<T> {
     #[inline]
     fn deserialize_by_key<K, D>(&mut self, keys: K, de: D) -> Result<usize, Error<D::Error>>
     where
         K: Keys,
         D: Deserializer<'de>,
     {
-        self.try_borrow_mut()
-            .or(Err(Traversal::Access(0, "Borrowed")))?
-            .deserialize_by_key(keys, de)
+        self.get_mut().deserialize_by_key(keys, de)
     }
 }
 
-impl<'de, T: TreeDeserialize<'de>> TreeDeserialize<'de> for RefCell<T> {
+impl<'de, T: TreeDeserialize<'de>> TreeDeserialize<'de> for &RefCell<T> {
     #[inline]
     fn deserialize_by_key<K, D>(&mut self, keys: K, de: D) -> Result<usize, Error<D::Error>>
     where
         K: Keys,
         D: Deserializer<'de>,
     {
-        self.get_mut().deserialize_by_key(keys, de)
+        self.try_borrow_mut()
+            .or(Err(Traversal::Access(0, "Borrowed")))?
+            .deserialize_by_key(keys, de)
     }
 }
 
@@ -1077,7 +1059,7 @@ mod _alloc {
             S: Serializer,
         {
             self.upgrade()
-                .ok_or(Traversal::Access(0, "Dropped"))?
+                .ok_or(Traversal::Absent(0))?
                 .serialize_by_key(keys, ser)
         }
     }
@@ -1090,7 +1072,7 @@ mod _alloc {
             D: Deserializer<'de>,
         {
             self.upgrade()
-                .ok_or(Traversal::Access(0, "Dropped"))?
+                .ok_or(Traversal::Absent(0))?
                 .deserialize_by_key(keys, de)
         }
     }
@@ -1201,7 +1183,7 @@ mod _alloc {
             S: Serializer,
         {
             self.upgrade()
-                .ok_or(Traversal::Access(0, "Dropped"))?
+                .ok_or(Traversal::Absent(0))?
                 .serialize_by_key(keys, ser)
         }
     }
@@ -1214,7 +1196,7 @@ mod _alloc {
             D: Deserializer<'de>,
         {
             self.upgrade()
-                .ok_or(Traversal::Access(0, "Dropped"))?
+                .ok_or(Traversal::Absent(0))?
                 .deserialize_by_key(keys, de)
         }
     }
@@ -1274,28 +1256,28 @@ mod _std {
         }
     }
 
-    impl<'de, T: TreeDeserialize<'de>> TreeDeserialize<'de> for &Mutex<T> {
+    impl<'de, T: TreeDeserialize<'de>> TreeDeserialize<'de> for Mutex<T> {
         #[inline]
         fn deserialize_by_key<K, D>(&mut self, keys: K, de: D) -> Result<usize, Error<D::Error>>
         where
             K: Keys,
             D: Deserializer<'de>,
         {
-            (*self)
-                .lock()
+            self.get_mut()
                 .or(Err(Traversal::Access(0, "Poisoned")))?
                 .deserialize_by_key(keys, de)
         }
     }
 
-    impl<'de, T: TreeDeserialize<'de>> TreeDeserialize<'de> for Mutex<T> {
+    impl<'de, T: TreeDeserialize<'de>> TreeDeserialize<'de> for &Mutex<T> {
         #[inline]
         fn deserialize_by_key<K, D>(&mut self, keys: K, de: D) -> Result<usize, Error<D::Error>>
         where
             K: Keys,
             D: Deserializer<'de>,
         {
-            self.get_mut()
+            (*self)
+                .lock()
                 .or(Err(Traversal::Access(0, "Poisoned")))?
                 .deserialize_by_key(keys, de)
         }
diff --git a/miniconf/src/lib.rs b/miniconf/src/lib.rs
index 209ca7a7..b7a5b26c 100644
--- a/miniconf/src/lib.rs
+++ b/miniconf/src/lib.rs
@@ -1,5 +1,5 @@
 #![cfg_attr(not(any(test, feature = "std")), no_std)]
-#![doc = include_str!("../README.md")]
+#![cfg_attr(all(feature = "derive", feature = "json-core"), doc = include_str!("../README.md"))]
 #![deny(rust_2018_compatibility)]
 #![deny(rust_2018_idioms)]
 #![warn(missing_docs)]
diff --git a/miniconf/tests/basic.rs b/miniconf/tests/basic.rs
index 57439b2d..c31a0a06 100644
--- a/miniconf/tests/basic.rs
+++ b/miniconf/tests/basic.rs
@@ -71,3 +71,12 @@ fn tuple() {
     }
     assert_eq!(s, (9.into(), (9.into(), 9.into()), [9.into(); 3]));
 }
+
+#[test]
+fn cell() {
+    use core::cell::RefCell;
+
+    let c: RefCell<Leaf<i32>> = Default::default();
+    let mut r = &c;
+    common::set_get(&mut r, "", b"9");
+}