diff --git a/src/map.rs b/src/map.rs
index 5bb4a9d358..18c2b46d3b 100644
--- a/src/map.rs
+++ b/src/map.rs
@@ -190,6 +190,7 @@ pub enum DefaultHashBuilder {}
 ///     // use the values stored in map
 /// }
 /// ```
+#[repr(C)]
 #[derive(Clone)]
 pub struct HashMap<K, V, S = DefaultHashBuilder> {
     pub(crate) hash_builder: S,
diff --git a/src/raw/mod.rs b/src/raw/mod.rs
index 1a04b9ac1f..c105c5a1ce 100644
--- a/src/raw/mod.rs
+++ b/src/raw/mod.rs
@@ -329,6 +329,7 @@ impl<T> Bucket<T> {
 }
 
 /// A raw hash table with an unsafe API.
+#[repr(C)]
 pub struct RawTable<T> {
     // Mask to get an index from a hash value. The value is one less than the
     // number of buckets in the table.