diff --git a/rcl/src/rcl/graph.c b/rcl/src/rcl/graph.c
index 3e63c45dd..8c6b7c738 100644
--- a/rcl/src/rcl/graph.c
+++ b/rcl/src/rcl/graph.c
@@ -353,7 +353,7 @@ rcl_get_node_names(
     }
   }
   // Check that none of the node namespaces are NULL
-  for (size_t i = 0u; i < node_names->size; ++i) {
+  for (size_t i = 0u; i < node_namespaces->size; ++i) {
     if (!node_namespaces->data[i]) {
       RCL_SET_ERROR_MSG("NULL node namespace returned by the RMW layer");
       return RCL_RET_ERROR;