diff --git a/src/graph/inference/graph_blockmodel.hh b/src/graph/inference/graph_blockmodel.hh
index e9df4f1f4abd1c379dd9c23c2521612e573a157d..2786c1ef74641c611f031196f7db66355ebf111f 100644
--- a/src/graph/inference/graph_blockmodel.hh
+++ b/src/graph/inference/graph_blockmodel.hh
@@ -84,7 +84,7 @@ enum weight_type
     ((brec,, eprop_map_t<std::vector<double>>::type, 0))                       \
     ((bdrec,, eprop_map_t<std::vector<double>>::type, 0))                      \
     ((brecsum,, vprop_map_t<double>::type, 0))                                 \
-    ((wparams,, std::vector<std::vector<double>>, 0))                          \
+    ((wparams, &, std::vector<std::vector<double>>&, 0))                       \
     ((ignore_degrees,, typename vprop_map_t<uint8_t>::type, 0))                \
     ((bignore_degrees,, typename vprop_map_t<uint8_t>::type, 0))               \
     ((allow_empty,, bool, 0))
diff --git a/src/graph_tool/inference/blockmodel.py b/src/graph_tool/inference/blockmodel.py
index 3930a306e2beb7332aad699d36ce382c3756626e..313d915c8422205ae5b0268bd27491bd00adb0a8 100644
--- a/src/graph_tool/inference/blockmodel.py
+++ b/src/graph_tool/inference/blockmodel.py
@@ -470,7 +470,7 @@ class BlockState(object):
 
             ks = list(defaults.keys())
             defaults.update(rec_params[i])
-            rec_params[i] = dict(**defaults)
+            rec_params[i] = defaults.copy()
             for k in ks:
                 ps.append(defaults.pop(k))
             if len(defaults) > 0: