diff --git a/sbe/__init__.py b/sbe/__init__.py
index 73a1081..f38a17b 100644
--- a/sbe/__init__.py
+++ b/sbe/__init__.py
@@ -373,7 +373,7 @@ def hydrate(self, offset: int):
                 p1.offset = cursor
                 p1.hydrate()
                 self.pointers[k] = p1
-                cursor += p1.numInGroup * p1.blockLength
+                cursor += p1.numInGroup * p1.blockLength + p.num_in_group_pointer.size + p.block_length_pointer.size
                 seen_group = True
             else:
                 assert not seen_group
@@ -1040,7 +1040,7 @@ def _walk_fields_decode(schema: Schema, rv: dict, fields: List[Union[Group, Fiel
             _walk_fields_decode_composite(schema, rv[f.name], f.type, vals, cursor)
 
         else:
-            if f.type.presence != Presence.CONSTANT:
+            if isinstance(f.type, PrimitiveType) or f.type.presence != Presence.CONSTANT:
                 _decode_value(schema, rv, f.name, f.type, vals, cursor)
 
 def _parse_schema(f: TextIO) -> Schema:
diff --git a/tests/dat/example-schema.xml b/tests/dat/example-schema.xml
index c646a33..b6c5776 100644
--- a/tests/dat/example-schema.xml
+++ b/tests/dat/example-schema.xml
@@ -84,4 +84,13 @@
             <field name="numbers" id="1" type="someNumbers"/>
         </group>
     </sbe:message>
+    <sbe:message name="TestMultipleGroups" id="4" blockLength="4">
+        <field name="year" id="1" type="ModelYear"/>
+        <group name="AGroup" id="2" dimensionType="groupSizeEncoding">
+            <field name="numbers" id="1" type="someNumbers"/>
+        </group>
+        <group name="BGroup" id="2" dimensionType="groupSizeEncoding">
+            <field name="numbers" id="1" type="someNumbers"/>
+        </group>
+    </sbe:message>
 </sbe:messageSchema>
diff --git a/tests/test_sbe.py b/tests/test_sbe.py
index 587033b..5163301 100644
--- a/tests/test_sbe.py
+++ b/tests/test_sbe.py
@@ -38,3 +38,22 @@ def test_blockLength():
         decoded  = s.decode(encoded)
         assert decoded.value['year'] == 1990
         assert decoded.value['AGroup'][1]['numbers'] == 456
+
+def test_multiple_groups():
+    with open("tests/dat/example-schema.xml", "r", encoding="utf-8") as f:
+        s = sbe.Schema.parse(f)
+        msg = s.messages[4]
+
+        encoded = s.encode(
+            msg,
+            {
+                "year": 1990,
+                "AGroup": [{"numbers": 123}, {"numbers": 456}],
+                "BGroup": [{"numbers": 654}, {"numbers": 321}],
+            },
+        )
+
+        decoded = s.wrap(encoded)
+        assert decoded.body["year"] == 1990
+        assert decoded.body["AGroup"][1]["numbers"] == 456
+        assert decoded.body["BGroup"][1]["numbers"] == 321