diff --git a/src/shape.rs b/src/shape.rs
index e3595b6..6ca3dbd 100644
--- a/src/shape.rs
+++ b/src/shape.rs
@@ -3,7 +3,7 @@
 // TODO: handle recursive types!
 use crate::traits::ShapeContext;
 use crate::BinProtShape;
-use std::collections::BTreeMap;
+use std::collections::{BTreeMap, HashMap};
 
 // In the OCaml version, uuids are used as strings.
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -235,6 +235,32 @@ impl<T: BinProtShape> BinProtShape for Vec<T> {
     }
 }
 
+fn iterable_binable1_shape(caller_identity: Uuid, bin_shape_el: Shape) -> Shape {
+    Shape::Base(
+        caller_identity,
+        vec![Shape::Base(Uuid::from("ac8a9ff4-4994-11e6-9a1b-9fb4e933bd9d"), vec![bin_shape_el])],
+    )
+}
+
+impl<K: BinProtShape, V: BinProtShape, S> BinProtShape for HashMap<K, V, S>
+where
+    S: 'static,
+{
+    fn binprot_shape_impl(c: &mut ShapeContext) -> Shape {
+        let caller_identity = Uuid::from("8fabab0a-4992-11e6-8cca-9ba2c4686d9e");
+        let bin_shape_el = Shape::Tuple(vec![K::binprot_shape_loop(c), V::binprot_shape_loop(c)]);
+        iterable_binable1_shape(caller_identity, bin_shape_el)
+    }
+}
+
+impl<K: BinProtShape, V: BinProtShape> BinProtShape for BTreeMap<K, V> {
+    fn binprot_shape_impl(c: &mut ShapeContext) -> Shape {
+        let caller_identity = Uuid::from("dfb300f8-4992-11e6-9c15-73a2ac6b815c");
+        let bin_shape_el = Shape::Tuple(vec![K::binprot_shape_loop(c), V::binprot_shape_loop(c)]);
+        iterable_binable1_shape(caller_identity, bin_shape_el)
+    }
+}
+
 impl<T: BinProtShape> BinProtShape for Option<T> {
     fn binprot_shape_impl(c: &mut ShapeContext) -> Shape {
         Shape::Base(Uuid::from("option"), vec![T::binprot_shape_loop(c)])
@@ -297,5 +323,13 @@ mod tests {
             Shape::Application(Box::new(inner), vec![])
         };
         assert_eq!(digest_str(&shape_rec), "2e92d51efb901fcf492f243fc1c3601d");
+        let shape_i64_i64_hashtbl = {
+            std::collections::HashMap::<i64, i64>::binprot_shape_impl(&mut ShapeContext::default())
+        };
+        assert_eq!(digest_str(&shape_i64_i64_hashtbl), "1fd943a5d8026fbd3e6746c972ab2127");
+        let shape_i64_i64_btreemap = {
+            std::collections::BTreeMap::<i64, i64>::binprot_shape_impl(&mut ShapeContext::default())
+        };
+        assert_eq!(digest_str(&shape_i64_i64_btreemap), "ed73a010af8ffc32cab7411d6be2d676");
     }
 }