diff --git a/ff/Cargo.toml b/ff/Cargo.toml
index 9ac1f1e..94480b0 100644
--- a/ff/Cargo.toml
+++ b/ff/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "ff"
-version = "0.5.0"
+version = "0.5.2"
 authors = ["Sean Bowe <ewillbefull@gmail.com>"]
 description = "Library for building and interfacing with finite fields"
 readme = "README.md"
@@ -12,7 +12,7 @@ edition = "2018"
 
 [dependencies]
 byteorder = "1"
-ff_derive = { version = "0.4.0", path = "ff_derive", optional = true }
+ff_derive = { version = "^0.4.1", path = "ff_derive", optional = true }
 rand_core = "0.5"
 
 [features]
diff --git a/ff/README.md b/ff/README.md
index c3127d8..57ef693 100644
--- a/ff/README.md
+++ b/ff/README.md
@@ -12,7 +12,7 @@ Add the `ff` crate to your `Cargo.toml`:
 
 ```toml
 [dependencies]
-ff = "0.4"
+ff = "0.5"
 ```
 
 The `ff` crate contains `Field`, `PrimeField`, `PrimeFieldRepr` and `SqrtField` traits.
diff --git a/ff/ff_derive/Cargo.toml b/ff/ff_derive/Cargo.toml
index 88ba23e..04a9bc2 100644
--- a/ff/ff_derive/Cargo.toml
+++ b/ff/ff_derive/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "ff_derive"
-version = "0.4.0"
+version = "0.4.1"
 authors = ["Sean Bowe <ewillbefull@gmail.com>"]
 description = "Procedural macro library used to build custom prime field implementations"
 documentation = "https://docs.rs/ff/"
diff --git a/ff/ff_derive/src/lib.rs b/ff/ff_derive/src/lib.rs
index d47ec12..813efe8 100644
--- a/ff/ff_derive/src/lib.rs
+++ b/ff/ff_derive/src/lib.rs
@@ -877,7 +877,7 @@ fn prime_field_impl(
 
         impl ::ff::Field for #name {
             /// Computes a uniformly random element using rejection sampling.
-            fn random<R: ::rand_core::RngCore>(rng: &mut R) -> Self {
+            fn random<R: ::rand_core::RngCore + ?std::marker::Sized>(rng: &mut R) -> Self {
                 loop {
                     let mut tmp = {
                         let mut repr = [0u64; #limbs];
diff --git a/ff/src/lib.rs b/ff/src/lib.rs
index b50cbd5..7662783 100644
--- a/ff/src/lib.rs
+++ b/ff/src/lib.rs
@@ -17,7 +17,7 @@ pub trait Field:
     Sized + Eq + Copy + Clone + Send + Sync + fmt::Debug + fmt::Display + 'static
 {
     /// Returns an element chosen uniformly at random using a user-provided RNG.
-    fn random<R: RngCore>(rng: &mut R) -> Self;
+    fn random<R: RngCore + ?std::marker::Sized>(rng: &mut R) -> Self;
 
     /// Returns the zero element of the field, the additive identity.
     fn zero() -> Self;