diff --git a/lib/prism/parse_result/newlines.rb b/lib/prism/parse_result/newlines.rb
index a04fa78a75..37f64f8ae2 100644
--- a/lib/prism/parse_result/newlines.rb
+++ b/lib/prism/parse_result/newlines.rb
@@ -63,7 +63,7 @@ module Prism
 
   class Node
     def newline_flag? # :nodoc:
-      @newline_flag ? true : false
+      !!defined?(@newline_flag)
     end
 
     def newline_flag!(lines) # :nodoc:
diff --git a/prism/prism.c b/prism/prism.c
index 6f8d5b005d..ffa5d3ddc4 100644
--- a/prism/prism.c
+++ b/prism/prism.c
@@ -21219,6 +21219,11 @@ parse_expression_infix(pm_parser_t *parser, pm_node_t *node, pm_binding_power_t
                     return result;
                 }
                 case PM_LOCAL_VARIABLE_READ_NODE: {
+                    if (pm_token_is_numbered_parameter(node->location.start, node->location.end)) {
+                        PM_PARSER_ERR_FORMAT(parser, node->location.start, node->location.end, PM_ERR_PARAMETER_NUMBERED_RESERVED, node->location.start);
+                        parse_target_implicit_parameter(parser, node);
+                    }
+
                     pm_local_variable_read_node_t *cast = (pm_local_variable_read_node_t *) node;
                     parser_lex(parser);
 
@@ -21337,6 +21342,11 @@ parse_expression_infix(pm_parser_t *parser, pm_node_t *node, pm_binding_power_t
                     return result;
                 }
                 case PM_LOCAL_VARIABLE_READ_NODE: {
+                    if (pm_token_is_numbered_parameter(node->location.start, node->location.end)) {
+                        PM_PARSER_ERR_FORMAT(parser, node->location.start, node->location.end, PM_ERR_PARAMETER_NUMBERED_RESERVED, node->location.start);
+                        parse_target_implicit_parameter(parser, node);
+                    }
+
                     pm_local_variable_read_node_t *cast = (pm_local_variable_read_node_t *) node;
                     parser_lex(parser);
 
@@ -21465,6 +21475,11 @@ parse_expression_infix(pm_parser_t *parser, pm_node_t *node, pm_binding_power_t
                     return result;
                 }
                 case PM_LOCAL_VARIABLE_READ_NODE: {
+                    if (pm_token_is_numbered_parameter(node->location.start, node->location.end)) {
+                        PM_PARSER_ERR_FORMAT(parser, node->location.start, node->location.end, PM_ERR_PARAMETER_NUMBERED_RESERVED, node->location.start);
+                        parse_target_implicit_parameter(parser, node);
+                    }
+
                     pm_local_variable_read_node_t *cast = (pm_local_variable_read_node_t *) node;
                     parser_lex(parser);
 
diff --git a/test/prism/errors/numbered_and_write.txt b/test/prism/errors/numbered_and_write.txt
new file mode 100644
index 0000000000..f80b97b2d5
--- /dev/null
+++ b/test/prism/errors/numbered_and_write.txt
@@ -0,0 +1,3 @@
+tap { _1 &&= 1 }
+      ^~ _1 is reserved for numbered parameters
+
diff --git a/test/prism/errors/numbered_operator_write.txt b/test/prism/errors/numbered_operator_write.txt
new file mode 100644
index 0000000000..70cd58c811
--- /dev/null
+++ b/test/prism/errors/numbered_operator_write.txt
@@ -0,0 +1,3 @@
+tap { _1 += 1 }
+      ^~ _1 is reserved for numbered parameters
+
diff --git a/test/prism/errors/numbered_or_write.txt b/test/prism/errors/numbered_or_write.txt
new file mode 100644
index 0000000000..b27495498d
--- /dev/null
+++ b/test/prism/errors/numbered_or_write.txt
@@ -0,0 +1,3 @@
+tap { _1 ||= 1 }
+      ^~ _1 is reserved for numbered parameters
+
diff --git a/test/prism/errors_test.rb b/test/prism/errors_test.rb
index cb2fd48d37..62bbd8458b 100644
--- a/test/prism/errors_test.rb
+++ b/test/prism/errors_test.rb
@@ -14,7 +14,10 @@ module Prism
         "targeting_numbered_parameter.txt",
         "defining_numbered_parameter.txt",
         "defining_numbered_parameter_2.txt",
-        "numbered_parameters_in_block_arguments.txt"
+        "numbered_parameters_in_block_arguments.txt",
+        "numbered_and_write.txt",
+        "numbered_or_write.txt",
+        "numbered_operator_write.txt"
       ]
     end