diff --git a/Lib/test/test_codeop.py b/Lib/test/test_codeop.py
index 5976303ad..d57452602 100644
--- a/Lib/test/test_codeop.py
+++ b/Lib/test/test_codeop.py
@@ -373,7 +373,7 @@ class CodeopTests(unittest.TestCase):
                 def foo(x,x):
                    pass
             """)
-        message = "duplicate argument 'x' in function definition"
+        message = "duplicate parameter 'x' in function definition"
         with self.assertRaisesRegex(SyntaxError, message):
             compiler(code, "<input>", 'exec')
 
diff --git a/Lib/test/test_positional_only_arg.py b/Lib/test/test_positional_only_arg.py
index eea062501..e412cb1d5 100644
--- a/Lib/test/test_positional_only_arg.py
+++ b/Lib/test/test_positional_only_arg.py
@@ -37,8 +37,8 @@ class PositionalOnlyTestCase(unittest.TestCase):
         check_syntax_error(self, "def f(/): pass")
         check_syntax_error(self, "def f(*, a, /): pass")
         check_syntax_error(self, "def f(*, /, a): pass")
-        check_syntax_error(self, "def f(a, /, a): pass", "duplicate argument 'a' in function definition")
-        check_syntax_error(self, "def f(a, /, *, a): pass", "duplicate argument 'a' in function definition")
+        check_syntax_error(self, "def f(a, /, a): pass", "duplicate parameter 'a' in function definition")
+        check_syntax_error(self, "def f(a, /, *, a): pass", "duplicate parameter 'a' in function definition")
         check_syntax_error(self, "def f(a, b/2, c): pass")
         check_syntax_error(self, "def f(a, /, c, /): pass")
         check_syntax_error(self, "def f(a, /, c, /, d): pass")
@@ -59,8 +59,8 @@ class PositionalOnlyTestCase(unittest.TestCase):
         check_syntax_error(self, "async def f(/): pass")
         check_syntax_error(self, "async def f(*, a, /): pass")
         check_syntax_error(self, "async def f(*, /, a): pass")
-        check_syntax_error(self, "async def f(a, /, a): pass", "duplicate argument 'a' in function definition")
-        check_syntax_error(self, "async def f(a, /, *, a): pass", "duplicate argument 'a' in function definition")
+        check_syntax_error(self, "async def f(a, /, a): pass", "duplicate parameter 'a' in function definition")
+        check_syntax_error(self, "async def f(a, /, *, a): pass", "duplicate parameter 'a' in function definition")
         check_syntax_error(self, "async def f(a, b/2, c): pass")
         check_syntax_error(self, "async def f(a, /, c, /): pass")
         check_syntax_error(self, "async def f(a, /, c, /, d): pass")
@@ -247,8 +247,8 @@ class PositionalOnlyTestCase(unittest.TestCase):
         check_syntax_error(self, "lambda /: None")
         check_syntax_error(self, "lambda *, a, /: None")
         check_syntax_error(self, "lambda *, /, a: None")
-        check_syntax_error(self, "lambda a, /, a: None", "duplicate argument 'a' in function definition")
-        check_syntax_error(self, "lambda a, /, *, a: None", "duplicate argument 'a' in function definition")
+        check_syntax_error(self, "lambda a, /, a: None", "duplicate parameter 'a' in function definition")
+        check_syntax_error(self, "lambda a, /, *, a: None", "duplicate parameter 'a' in function definition")
         check_syntax_error(self, "lambda a, /, b, /: None")
         check_syntax_error(self, "lambda a, /, b, /, c: None")
         check_syntax_error(self, "lambda a, /, b, /, c, *, d: None")
diff --git a/crates/codegen/src/symboltable.rs b/crates/codegen/src/symboltable.rs
index 4af1ee0be..292324263 100644
--- a/crates/codegen/src/symboltable.rs
+++ b/crates/codegen/src/symboltable.rs
@@ -1455,7 +1455,7 @@ impl SymbolTableBuilder {
         if table.symbols.contains_key(parameter.name.as_str()) {
             return Err(self.error_ranged(
                 format!(
-                    "duplicate argument '{}' in function definition",
+                    "duplicate parameter '{}' in function definition",
                     parameter.name
                 ),
                 parameter.name.range,
@@ -3204,7 +3204,7 @@ impl SymbolTableBuilder {
 
             if matches!(role, SymbolUsage::Parameter) && flags.contains(SymbolFlags::DEF_PARAM) {
                 return Err(SymbolTableError {
-                    error: format!("duplicate argument '{original_name}' in function definition"),
+                    error: format!("duplicate parameter '{original_name}' in function definition"),
                     location,
                     end_location,
                 });
@@ -3485,11 +3485,11 @@ mod tests {
     #[test]
     fn duplicate_parameter_check_uses_mangled_name_like_cpython() {
         let err = scan_source_result("class C:\n    def f(__x, _C__x):\n        pass\n")
-            .expect_err("expected duplicate argument after class-private mangling");
+            .expect_err("expected duplicate parameter after class-private mangling");
 
         assert_eq!(
             err.error,
-            "duplicate argument '_C__x' in function definition"
+            "duplicate parameter '_C__x' in function definition"
         );
     }