diff --git a/src/jsonapi_client/resourceobject.py b/src/jsonapi_client/resourceobject.py
index b499d7c..7898eb2 100644
--- a/src/jsonapi_client/resourceobject.py
+++ b/src/jsonapi_client/resourceobject.py
@@ -84,6 +84,8 @@ def __init__(self, data: dict,
 
         specification = self._schema.find_spec(self._resource.type, self._full_name)
 
+        # Using .pop() below modifies the data, so we make a shallow copy of it first
+        data = data.copy()
         # If there's schema for this object, we will use it to construct object.
         if specification:
             for field_name, field_spec in specification['properties'].items():