diff --git a/Cargo.toml b/Cargo.toml
index d2ae5fad83..3126de3c5e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,7 +11,7 @@
 [package]
 edition = "2021"
 name = "zerocopy"
-version = "0.7.2"
+version = "0.7.3"
 authors = ["Joshua Liebow-Feeser <joshlf@google.com>"]
 description = "Utilities for zero-copy parsing and serialization"
 license = "BSD-2-Clause"
@@ -55,7 +55,7 @@ simd-nightly = ["simd"]
 __internal_use_only_features_that_work_on_stable = ["alloc", "simd"]
 
 [dependencies]
-zerocopy-derive = { version = "=0.7.2", path = "zerocopy-derive", optional = true }
+zerocopy-derive = { version = "=0.7.3", path = "zerocopy-derive", optional = true }
 
 [dependencies.byteorder]
 version = "1.3"
@@ -66,7 +66,7 @@ optional = true
 # zerocopy-derive remain equal, even if the 'derive' feature isn't used.
 # See: https://github.com/matklad/macro-dep-test
 [target.'cfg(any())'.dependencies]
-zerocopy-derive = { version = "=0.7.2", path = "zerocopy-derive" }
+zerocopy-derive = { version = "=0.7.3", path = "zerocopy-derive" }
 
 [dev-dependencies]
 rand = "0.6"
@@ -78,4 +78,4 @@ static_assertions = "1.1"
 # CI test failures.
 trybuild = "=1.0.80"
 # In tests, unlike in production, zerocopy-derive is not optional
-zerocopy-derive = { version = "=0.7.2", path = "zerocopy-derive" }
+zerocopy-derive = { version = "=0.7.3", path = "zerocopy-derive" }
diff --git a/src/lib.rs b/src/lib.rs
index a40993b0ed..c462c15d7e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -996,13 +996,23 @@ safety_comment! {
     //
     /// SAFETY:
     /// - `FromZeroes`, `FromBytes`: `MaybeUninit<T>` has no restrictions on its
-    ///   contents.
+    ///   contents. Unfortunately, in addition to bit validity, `FromZeroes` and
+    ///   `FromBytes` also require that implementers contain no `UnsafeCell`s.
+    ///   Thus, we require `T: FromZeroes` and `T: FromBytes` in order to ensure
+    ///   that `T` - and thus `MaybeUninit<T>` - contains to `UnsafeCell`s.
+    ///   Thus, requiring that `T` implement each of these traits is sufficient
     /// - `Unaligned`: `MaybeUninit<T>` is guaranteed by its documentation [1]
     ///   to have the same alignment as `T`.
     ///
-    /// [1] https://doc.rust-lang.org/nightly/core/mem/union.MaybeUninit.html#layout-1
-    unsafe_impl!(T => FromZeroes for MaybeUninit<T>);
-    unsafe_impl!(T => FromBytes for MaybeUninit<T>);
+    /// [1]
+    /// https://doc.rust-lang.org/nightly/core/mem/union.MaybeUninit.html#layout-1
+    ///
+    /// TODO(https://github.com/google/zerocopy/issues/251): If we split
+    /// `FromBytes` and `RefFromBytes`, or if we introduce a separate
+    /// `NoCell`/`Freeze` trait, we can relax the trait bounds for `FromZeroes`
+    /// and `FromBytes`.
+    unsafe_impl!(T: FromZeroes => FromZeroes for MaybeUninit<T>);
+    unsafe_impl!(T: FromBytes => FromBytes for MaybeUninit<T>);
     unsafe_impl!(T: Unaligned => Unaligned for MaybeUninit<T>);
     assert_unaligned!(MaybeUninit<()>, MaybeUninit<u8>);
 }
@@ -4059,7 +4069,7 @@ mod tests {
         assert_impls!(ManuallyDrop<[NotZerocopy]>: !FromZeroes, !FromBytes, !AsBytes, !Unaligned);
 
         assert_impls!(MaybeUninit<u8>: FromZeroes, FromBytes, Unaligned, !AsBytes);
-        assert_impls!(MaybeUninit<NotZerocopy>: FromZeroes, FromBytes, !AsBytes, !Unaligned);
+        assert_impls!(MaybeUninit<NotZerocopy>: !FromZeroes, !FromBytes, !AsBytes, !Unaligned);
 
         assert_impls!(Wrapping<u8>: FromZeroes, FromBytes, AsBytes, Unaligned);
         assert_impls!(Wrapping<NotZerocopy>: !FromZeroes, !FromBytes, !AsBytes, !Unaligned);
diff --git a/zerocopy-derive/Cargo.toml b/zerocopy-derive/Cargo.toml
index 3f22d3c1b3..3d19d6ce16 100644
--- a/zerocopy-derive/Cargo.toml
+++ b/zerocopy-derive/Cargo.toml
@@ -5,7 +5,7 @@
 [package]
 edition = "2021"
 name = "zerocopy-derive"
-version = "0.7.2"
+version = "0.7.3"
 authors = ["Joshua Liebow-Feeser <joshlf@google.com>"]
 description = "Custom derive for traits from the zerocopy crate"
 license = "BSD-2-Clause"