diff --git a/extern/json b/extern/json
index 043441b..8030eb3 160000
--- a/extern/json
+++ b/extern/json
@@ -1 +1 @@
-Subproject commit 043441b2c4cbbb9cdaed954d6439bfdd6fc2f735
+Subproject commit 8030eb30b5c6db08228425f92065e0cad68cfe0c
diff --git a/src/core.cpp b/src/core.cpp
index d9f4f21..eb3775d 100644
--- a/src/core.cpp
+++ b/src/core.cpp
@@ -67,7 +67,7 @@ namespace riddle
             p->atoms.push_back(atm);
             q.pop();
             for (auto &parent : p->parents)
-                q.push(parent.operator->());
+                q.push(&*parent);
         }
         return atm;
     }
diff --git a/src/statement.cpp b/src/statement.cpp
index c8bb8e8..fe95c18 100644
--- a/src/statement.cpp
+++ b/src/statement.cpp
@@ -181,7 +181,7 @@ namespace riddle
                 }
             q.pop();
             for (auto &parent : p->get_parents())
-                q.push(parent.operator->());
+                q.push(&*parent);
         }
 
         auto atm = scp.get_core().new_atom(is_fact, pred, std::move(c_args));
diff --git a/src/type.cpp b/src/type.cpp
index 7a98e87..f5869cc 100644
--- a/src/type.cpp
+++ b/src/type.cpp
@@ -54,7 +54,7 @@ namespace riddle
                 if (tp == this)
                     return true;
                 for (const auto &e : tp->get_enums())
-                    q.push(e.operator->());
+                    q.push(&*e);
             }
         }
         return false;
@@ -94,7 +94,7 @@ namespace riddle
                 if (tp == this)
                     return true;
                 for (const auto &p : tp->parents)
-                    q.push(p.operator->());
+                    q.push(&*p);
             }
         }
         return false;
@@ -247,7 +247,7 @@ namespace riddle
             q.pop();
             tp->created_predicate(*predicates[name]);
             for (const auto &p : tp->parents)
-                q.push(p.operator->());
+                q.push(&*p);
         }
     }
 
@@ -272,7 +272,7 @@ namespace riddle
             q.pop();
             tp->instances.push_back(utils::s_ptr(itm));
             for (const auto &p : tp->parents)
-                q.push(p.operator->());
+                q.push(&*p);
         }
         return itm;
     }
@@ -294,7 +294,7 @@ namespace riddle
                 if (tp == this)
                     return true;
                 for (const auto &p : tp->parents)
-                    q.push(p.operator->());
+                    q.push(&*p);
             }
         }
         return false;
@@ -322,7 +322,7 @@ namespace riddle
             q.pop();
             p->atoms.push_back(atm);
             for (const auto &par : p->parents)
-                q.push(par.operator->());
+                q.push(&*par);
         }
         return atm;
     }