diff --git a/rcl/src/rcl/arguments.c b/rcl/src/rcl/arguments.c
index a9e5e6882..2f889f0db 100644
--- a/rcl/src/rcl/arguments.c
+++ b/rcl/src/rcl/arguments.c
@@ -1971,16 +1971,18 @@ _rcl_parse_param_rule(
   // TODO(hidmic): switch to _rcl_parse_resource_match() when parameter names
   //               are standardized to use slashes in lieu of dots.
   ret = _rcl_parse_param_name(&lex_lookahead, params->allocator, &param_name);
-  if (RCL_RET_OK != ret) {
-    if (RCL_RET_WRONG_LEXEME == ret) {
-      ret = RCL_RET_INVALID_PARAM_RULE;
-    }
-    goto cleanup;
+  if (RCL_RET_OK == ret) {
+    ret = rcl_lexer_lookahead2_expect(&lex_lookahead, RCL_LEXEME_SEPARATOR, NULL, NULL);
   }
-
-  ret = rcl_lexer_lookahead2_expect(&lex_lookahead, RCL_LEXEME_SEPARATOR, NULL, NULL);
-  if (RCL_RET_WRONG_LEXEME == ret) {
+  if (RCL_RET_WRONG_LEXEME == ret || RCL_RET_INVALID_REMAP_RULE == ret) {
+    rcl_error_string_t prev_error_string = rcl_get_error_string();
+    rcl_reset_error();
+    RCL_SET_ERROR_MSG_WITH_FORMAT_STRING(
+      "Parameter override rule must have the format 'name:=value'. Error: %s",
+      prev_error_string.str);
     ret = RCL_RET_INVALID_PARAM_RULE;
+  }
+  if (RCL_RET_OK != ret) {
     goto cleanup;
   }
 
diff --git a/rcl/test/rcl/test_arguments.cpp b/rcl/test/rcl/test_arguments.cpp
index 3d944f510..38b6b5e4e 100644
--- a/rcl/test/rcl/test_arguments.cpp
+++ b/rcl/test/rcl/test_arguments.cpp
@@ -293,6 +293,22 @@ TEST_F(TestArgumentsFixture, check_valid_vs_invalid_args) {
   EXPECT_FALSE(are_valid_ros_args({"--ros-args", "--log-file-name"}));
 }
 
+TEST_F(TestArgumentsFixture, test_parameter_override_missing_assignment_error) {
+  const char * const argv[] = {"process_name", "--ros-args", "-p", "bla"};
+  const int argc = sizeof(argv) / sizeof(const char *);
+  rcl_arguments_t parsed_args = rcl_get_zero_initialized_arguments();
+
+  EXPECT_EQ(
+    RCL_RET_INVALID_ROS_ARGS,
+    rcl_parse_arguments(argc, argv, rcl_get_default_allocator(), &parsed_args));
+  const std::string error_message = rcl_get_error_string().str;
+  EXPECT_NE(
+    std::string::npos,
+    error_message.find("Parameter override rule must have the format 'name:=value'"));
+  EXPECT_NE(std::string::npos, error_message.find("Expected lexeme type"));
+  rcl_reset_error();
+}
+
 TEST_F(TestArgumentsFixture, test_no_args) {
   rcl_arguments_t parsed_args = rcl_get_zero_initialized_arguments();
   rcl_ret_t ret = rcl_parse_arguments(0, NULL, rcl_get_default_allocator(), &parsed_args);