diff --git a/config.yml b/config.yml
index b37b98cbdf..f44dc6fa2b 100644
--- a/config.yml
+++ b/config.yml
@@ -1,5 +1,6 @@
 errors:
   - ALIAS_ARGUMENT
+  - ALIAS_ARGUMENT_GLOBAL_VARIABLE
   - ALIAS_ARGUMENT_NUMBERED_REFERENCE
   - AMPAMPEQ_MULTI_ASSIGN
   - ARGUMENT_AFTER_BLOCK
diff --git a/src/prism.c b/src/prism.c
index 8707330c95..ca4e78b225 100644
--- a/src/prism.c
+++ b/src/prism.c
@@ -18799,7 +18799,7 @@ parse_expression_prefix(pm_parser_t *parser, pm_binding_power_t binding_power, b
                             pm_parser_err_node(parser, old_name, PM_ERR_ALIAS_ARGUMENT_NUMBERED_REFERENCE);
                         }
                     } else {
-                        pm_parser_err_node(parser, old_name, PM_ERR_ALIAS_ARGUMENT);
+                        pm_parser_err_node(parser, old_name, PM_ERR_ALIAS_ARGUMENT_GLOBAL_VARIABLE);
                     }
 
                     return (pm_node_t *) pm_alias_global_variable_node_create(parser, &keyword, new_name, old_name);
diff --git a/templates/src/diagnostic.c.erb b/templates/src/diagnostic.c.erb
index 9a30a57e3b..af01f3e32a 100644
--- a/templates/src/diagnostic.c.erb
+++ b/templates/src/diagnostic.c.erb
@@ -86,6 +86,7 @@ static const pm_diagnostic_data_t diagnostic_messages[PM_DIAGNOSTIC_ID_MAX] = {
 
     // Errors that should raise syntax errors
     [PM_ERR_ALIAS_ARGUMENT]                     = { "invalid argument being passed to `alias`; expected a bare word, symbol, constant, or global variable", PM_ERROR_LEVEL_SYNTAX },
+    [PM_ERR_ALIAS_ARGUMENT_GLOBAL_VARIABLE]     = { "invalid argument being passed to `alias`; when aliasing global variables, both the old and new names must be global variables", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_ALIAS_ARGUMENT_NUMBERED_REFERENCE]  = { "invalid argument being passed to `alias`; can't make alias for the number variables", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_AMPAMPEQ_MULTI_ASSIGN]              = { "unexpected `&&=` in a multiple assignment", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_ARGUMENT_AFTER_BLOCK]               = { "unexpected argument after a block argument", PM_ERROR_LEVEL_SYNTAX },
diff --git a/test/prism/errors/aliasing_global_variable_with_non_global_variable.txt b/test/prism/errors/aliasing_global_variable_with_non_global_variable.txt
index b6f013bab5..c956e5fe77 100644
--- a/test/prism/errors/aliasing_global_variable_with_non_global_variable.txt
+++ b/test/prism/errors/aliasing_global_variable_with_non_global_variable.txt
@@ -1,3 +1,3 @@
 alias $a b
-         ^ invalid argument being passed to `alias`; expected a bare word, symbol, constant, or global variable
+         ^ invalid argument being passed to `alias`; when aliasing global variables, both the old and new names must be global variables