diff --git a/rcl_yaml_param_parser/src/parser.c b/rcl_yaml_param_parser/src/parser.c
index 5313edf..7851605 100644
--- a/rcl_yaml_param_parser/src/parser.c
+++ b/rcl_yaml_param_parser/src/parser.c
@@ -187,7 +187,14 @@ static rcl_ret_t add_name_to_ns(
       ns_len = strlen(cur_ns);
       name_len = strlen(name);
       sep_len = strlen(sep_str);
-      tot_len = ns_len + name_len + sep_len + 1U;
+      // Check the last sep_len characters of the current NS against the separator string.
+      if (strcmp(cur_ns + ns_len - sep_len, sep_str) == 0) {
+        // Current NS already ends with the separator: don't put another separator in.
+        sep_len = 0;
+        sep_str = "";
+      }
+
+      tot_len = ns_len + sep_len + name_len + 1U;
 
       if (tot_len > MAX_STRING_SIZE) {
         RCL_SET_ERROR_MSG("New namespace string is exceeding max string size",
diff --git a/rcl_yaml_param_parser/test/root_ns.yaml b/rcl_yaml_param_parser/test/root_ns.yaml
new file mode 100644
index 0000000..84ce013
--- /dev/null
+++ b/rcl_yaml_param_parser/test/root_ns.yaml
@@ -0,0 +1,7 @@
+# config/test_yaml
+---
+
+/:
+  my_node:
+    ros__parameters:
+      param_name: 'value'
diff --git a/rcl_yaml_param_parser/test/test_parse_yaml.cpp b/rcl_yaml_param_parser/test/test_parse_yaml.cpp
index 7d6815b..738cdd5 100644
--- a/rcl_yaml_param_parser/test/test_parse_yaml.cpp
+++ b/rcl_yaml_param_parser/test/test_parse_yaml.cpp
@@ -62,6 +62,31 @@ TEST(test_file_parser, multi_ns_correct_syntax) {
   allocator.deallocate(path, allocator.state);
 }
 
+TEST(test_file_parser, root_ns) {
+  rcutils_reset_error();
+  EXPECT_TRUE(rcutils_get_cwd(cur_dir, 1024));
+  rcutils_allocator_t allocator = rcutils_get_default_allocator();
+  char * test_path = rcutils_join_path(cur_dir, "test", allocator);
+  char * path = rcutils_join_path(test_path, "root_ns.yaml", allocator);
+  fprintf(stderr, "cur_path: %s\n", path);
+  EXPECT_TRUE(rcutils_exists(path));
+  rcl_params_t * params_hdl = rcl_yaml_node_struct_init(allocator);
+  EXPECT_FALSE(NULL == params_hdl);
+  bool res = rcl_parse_yaml_file(path, params_hdl);
+  fprintf(stderr, "%s\n", rcutils_get_error_string_safe());
+  EXPECT_TRUE(res);
+  rcl_yaml_node_struct_print(params_hdl);
+
+  // Check that there is only one forward slash in the node's FQN.
+  // (Regression test for https://github.com/ros2/rcl/pull/299).
+  ASSERT_EQ(1u, params_hdl->num_nodes);
+  ASSERT_STREQ("/my_node", params_hdl->node_names[0]);
+
+  rcl_yaml_node_struct_fini(params_hdl);
+  allocator.deallocate(test_path, allocator.state);
+  allocator.deallocate(path, allocator.state);
+}
+
 TEST(test_file_parser, seq_map1) {
   rcutils_reset_error();
   EXPECT_TRUE(rcutils_get_cwd(cur_dir, 1024));