diff --git a/src/libsysprof-analyze/sysprof-callgraph-symbol.c b/src/libsysprof-analyze/sysprof-callgraph-symbol.c
index 370d5440..5d7fab42 100644
--- a/src/libsysprof-analyze/sysprof-callgraph-symbol.c
+++ b/src/libsysprof-analyze/sysprof-callgraph-symbol.c
@@ -201,7 +201,7 @@ sysprof_callgraph_symbol_list_model_get_item (GListModel *model,
 {
   SysprofCallgraphSymbolListModel *self = (SysprofCallgraphSymbolListModel *)model;
 
-  if (self->symbols == NULL || position >= self->symbols->len)
+  if (self->symbols == NULL || position >= self->symbols->len || self->callgraph == NULL)
     return NULL;
 
   return _sysprof_callgraph_symbol_new (self->callgraph,
@@ -227,7 +227,7 @@ sysprof_callgraph_symbol_list_model_dispose (GObject *object)
   SysprofCallgraphSymbolListModel *self = (SysprofCallgraphSymbolListModel *)object;
 
   g_clear_pointer (&self->symbols, g_ptr_array_unref);
-  g_clear_object (&self->callgraph);
+  g_clear_weak_pointer (&self->callgraph);
 
   G_OBJECT_CLASS (sysprof_callgraph_symbol_parent_class)->dispose (object);
 }
@@ -254,7 +254,7 @@ _sysprof_callgraph_symbol_list_model_new (SysprofCallgraph *callgraph,
   g_return_val_if_fail (SYSPROF_IS_CALLGRAPH (callgraph), NULL);
 
   self = g_object_new (SYSPROF_TYPE_CALLGRAPH_SYMBOL_LIST_MODEL, NULL);
-  self->callgraph = g_object_ref (callgraph);
+  g_set_weak_pointer (&self->callgraph, callgraph);
 
   if (symbols != NULL)
     self->symbols = g_ptr_array_ref (symbols);