diff --git a/src/evalfunc.c b/src/evalfunc.c
index 0e800c2..61cca01 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -275,6 +275,7 @@
     int		arg_count;	// actual argument count
     type_T	**arg_types;	// list of argument types
     int		arg_idx;	// current argument index (first arg is zero)
+    cctx_T	*arg_cctx;
 } argcontext_T;
 
 // A function to check one argument type.  The first argument is the type to
@@ -283,6 +284,22 @@
 typedef int (*argcheck_T)(type_T *, argcontext_T *);
 
 /*
+ * Call need_type() to check an argument type.
+ */
+    static int
+check_arg_type(
+	type_T		*expected,
+	type_T		*actual,
+	argcontext_T	*context)
+{
+    // TODO: would be useful to know if "actual" is a constant and pass it to
+    // need_type() to get a compile time error if possible.
+    return need_type(actual, expected,
+	    context->arg_idx - context->arg_count, context->arg_idx + 1,
+	    context->arg_cctx, FALSE, FALSE);
+}
+
+/*
  * Check "type" is a float or a number.
  */
     static int
@@ -301,7 +318,7 @@
     static int
 arg_number(type_T *type, argcontext_T *context)
 {
-    return check_arg_type(&t_number, type, context->arg_idx + 1);
+    return check_arg_type(&t_number, type, context);
 }
 
 /*
@@ -310,7 +327,7 @@
     static int
 arg_string(type_T *type, argcontext_T *context)
 {
-    return check_arg_type(&t_string, type, context->arg_idx + 1);
+    return check_arg_type(&t_string, type, context);
 }
 
 /*
@@ -348,7 +365,7 @@
 {
     type_T *prev_type = context->arg_types[context->arg_idx - 1];
 
-    return check_arg_type(prev_type, type, context->arg_idx + 1);
+    return check_arg_type(prev_type, type, context);
 }
 
 /*
@@ -362,7 +379,7 @@
     type_T *prev_type = context->arg_types[context->arg_idx - 1];
 
     if (prev_type->tt_type != context->arg_types[context->arg_idx]->tt_type)
-	return check_arg_type(prev_type, type, context->arg_idx + 1);
+	return check_arg_type(prev_type, type, context);
     return OK;
 }
 
@@ -384,7 +401,7 @@
 	// probably VAR_ANY, can't check
 	return OK;
 
-    return check_arg_type(expected, type, context->arg_idx + 1);
+    return check_arg_type(expected, type, context);
 }
 
 /*
@@ -1931,7 +1948,11 @@
  * Return FAIL and gives an error message when a type is wrong.
  */
     int
-internal_func_check_arg_types(type_T **types, int idx, int argcount)
+internal_func_check_arg_types(
+	type_T	**types,
+	int	idx,
+	int	argcount,
+	cctx_T	*cctx)
 {
     argcheck_T	*argchecks = global_functions[idx].f_argcheck;
     int		i;
@@ -1942,6 +1963,7 @@
 
 	context.arg_count = argcount;
 	context.arg_types = types;
+	context.arg_cctx = cctx;
 	for (i = 0; i < argcount; ++i)
 	    if (argchecks[i] != NULL)
 	    {
diff --git a/src/proto/evalfunc.pro b/src/proto/evalfunc.pro
index ad4b98a..13dffac 100644
--- a/src/proto/evalfunc.pro
+++ b/src/proto/evalfunc.pro
@@ -4,7 +4,7 @@
 int find_internal_func(char_u *name);
 int has_internal_func(char_u *name);
 char *internal_func_name(int idx);
-int internal_func_check_arg_types(type_T **types, int idx, int argcount);
+int internal_func_check_arg_types(type_T **types, int idx, int argcount, cctx_T *cctx);
 type_T *internal_func_ret_type(int idx, int argcount, type_T **argtypes);
 int internal_func_is_map(int idx);
 int check_internal_func(int idx, int argcount);
diff --git a/src/proto/vim9compile.pro b/src/proto/vim9compile.pro
index 7800d3b..d1d1b0c 100644
--- a/src/proto/vim9compile.pro
+++ b/src/proto/vim9compile.pro
@@ -2,6 +2,7 @@
 int check_defined(char_u *p, size_t len, cctx_T *cctx);
 int check_compare_types(exprtype_T type, typval_T *tv1, typval_T *tv2);
 int use_typecheck(type_T *actual, type_T *expected);
+int need_type(type_T *actual, type_T *expected, int offset, int arg_idx, cctx_T *cctx, int silent, int actual_is_const);
 int get_script_item_idx(int sid, char_u *name, int check_writable, cctx_T *cctx);
 imported_T *find_imported(char_u *name, size_t len, cctx_T *cctx);
 imported_T *find_imported_in_script(char_u *name, size_t len, int sid);
diff --git a/src/proto/vim9type.pro b/src/proto/vim9type.pro
index 316c650..f7b472c 100644
--- a/src/proto/vim9type.pro
+++ b/src/proto/vim9type.pro
@@ -15,7 +15,6 @@
 void type_mismatch(type_T *expected, type_T *actual);
 void arg_type_mismatch(type_T *expected, type_T *actual, int argidx);
 int check_type(type_T *expected, type_T *actual, int give_msg, int argidx);
-int check_arg_type(type_T *expected, type_T *actual, int argidx);
 int check_argument_types(type_T *type, typval_T *argvars, int argcount, char_u *name);
 char_u *skip_type(char_u *start, int optional);
 type_T *parse_type(char_u **arg, garray_T *type_gap, int give_error);
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index f1c5de1..180070e 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -241,6 +241,9 @@
   CheckDefFailure(['extend({a: 1}, 42)'], 'E1013: Argument 2: type mismatch, expected dict<number> but got number')
   CheckDefFailure(['extend({a: 1}, {b: "x"})'], 'E1013: Argument 2: type mismatch, expected dict<number> but got dict<string>')
   CheckDefFailure(['extend({a: 1}, {b: 2}, 1)'], 'E1013: Argument 3: type mismatch, expected string but got number')
+
+  CheckDefFailure(['extend([1], ["b"])'], 'E1013: Argument 2: type mismatch, expected list<number> but got list<string>')
+  CheckDefExecFailure(['extend([1], ["b", 1])'], 'E1012: Type mismatch; expected list<number> but got list<any>')
 enddef
 
 def Test_extendnew()
diff --git a/src/version.c b/src/version.c
index 8dccaf2..73bdc24 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2362,
+/**/
     2361,
 /**/
     2360,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index b0b5973..fb7aedd 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -878,11 +878,12 @@
  * If "actual_is_const" is TRUE then the type won't change at runtime, do not
  * generate a TYPECHECK.
  */
-    static int
+    int
 need_type(
 	type_T	*actual,
 	type_T	*expected,
 	int	offset,
+	int	arg_idx,
 	cctx_T	*cctx,
 	int	silent,
 	int	actual_is_const)
@@ -896,7 +897,7 @@
 	return OK;
     }
 
-    if (check_type(expected, actual, FALSE, 0) == OK)
+    if (check_type(expected, actual, FALSE, arg_idx) == OK)
 	return OK;
 
     // If the actual type can be the expected type add a runtime check.
@@ -908,7 +909,7 @@
     }
 
     if (!silent)
-	type_mismatch(expected, actual);
+	arg_type_mismatch(expected, actual, arg_idx);
     return FAIL;
 }
 
@@ -931,7 +932,7 @@
 	// This requires a runtime type check.
 	return generate_COND2BOOL(cctx);
 
-    return need_type(type, &t_bool, -1, cctx, FALSE, FALSE);
+    return need_type(type, &t_bool, -1, 0, cctx, FALSE, FALSE);
 }
 
 /*
@@ -1613,7 +1614,8 @@
     {
 	// Check the types of the arguments.
 	argtypes = ((type_T **)stack->ga_data) + stack->ga_len - argcount;
-	if (internal_func_check_arg_types(argtypes, func_idx, argcount) == FAIL)
+	if (internal_func_check_arg_types(argtypes, func_idx, argcount,
+								 cctx) == FAIL)
 	    return FAIL;
 	if (internal_func_is_map(func_idx))
 	    maptype = *argtypes;
@@ -1656,7 +1658,7 @@
     list_type = ((type_T **)stack->ga_data)[stack->ga_len - 2];
     item_type = ((type_T **)stack->ga_data)[stack->ga_len - 1];
     expected = list_type->tt_member;
-    if (need_type(item_type, expected, -1, cctx, FALSE, FALSE) == FAIL)
+    if (need_type(item_type, expected, -1, 0, cctx, FALSE, FALSE) == FAIL)
 	return FAIL;
 
     if (generate_instr(cctx, ISN_LISTAPPEND) == NULL)
@@ -1678,7 +1680,7 @@
 
     // Caller already checked that blob_type is a blob.
     item_type = ((type_T **)stack->ga_data)[stack->ga_len - 1];
-    if (need_type(item_type, &t_number, -1, cctx, FALSE, FALSE) == FAIL)
+    if (need_type(item_type, &t_number, -1, 0, cctx, FALSE, FALSE) == FAIL)
 	return FAIL;
 
     if (generate_instr(cctx, ISN_BLOBAPPEND) == NULL)
@@ -1733,7 +1735,7 @@
 	    else
 		expected = ufunc->uf_va_type->tt_member;
 	    actual = ((type_T **)stack->ga_data)[stack->ga_len - argcount + i];
-	    if (need_type(actual, expected, -argcount + i, cctx,
+	    if (need_type(actual, expected, -argcount + i, 0, cctx,
 							  TRUE, FALSE) == FAIL)
 	    {
 		arg_type_mismatch(expected, actual, i + 1);
@@ -1850,7 +1852,7 @@
 					     type->tt_argcount - 1]->tt_member;
 		    else
 			expected = type->tt_args[i];
-		    if (need_type(actual, expected, offset,
+		    if (need_type(actual, expected, offset, 0,
 						    cctx, TRUE, FALSE) == FAIL)
 		    {
 			arg_type_mismatch(expected, actual, i + 1);
@@ -3135,7 +3137,7 @@
 	    {
 		type_T *keytype = ((type_T **)stack->ga_data)
 						       [stack->ga_len - 1];
-		if (need_type(keytype, &t_string, -1, cctx,
+		if (need_type(keytype, &t_string, -1, 0, cctx,
 						     FALSE, FALSE) == FAIL)
 		    return FAIL;
 	    }
@@ -3808,13 +3810,13 @@
 		vtype = VAR_DICT;
 	    if (vtype == VAR_STRING || vtype == VAR_LIST || vtype == VAR_BLOB)
 	    {
-		if (need_type(valtype, &t_number, -1, cctx,
+		if (need_type(valtype, &t_number, -1, 0, cctx,
 							 FALSE, FALSE) == FAIL)
 		    return FAIL;
 		if (is_slice)
 		{
 		    valtype = ((type_T **)stack->ga_data)[stack->ga_len - 2];
-		    if (need_type(valtype, &t_number, -2, cctx,
+		    if (need_type(valtype, &t_number, -2, 0, cctx,
 							 FALSE, FALSE) == FAIL)
 			return FAIL;
 		}
@@ -3836,7 +3838,7 @@
 		}
 		else
 		{
-		    if (need_type(*typep, &t_dict_any, -2, cctx,
+		    if (need_type(*typep, &t_dict_any, -2, 0, cctx,
 							 FALSE, FALSE) == FAIL)
 			return FAIL;
 		    *typep = &t_any;
@@ -4235,7 +4237,7 @@
 	actual = ((type_T **)stack->ga_data)[stack->ga_len - 1];
 	if (check_type(want_type, actual, FALSE, 0) == FAIL)
 	{
-	    if (need_type(actual, want_type, -1, cctx, FALSE, FALSE) == FAIL)
+	    if (need_type(actual, want_type, -1, 0, cctx, FALSE, FALSE) == FAIL)
 		return FAIL;
 	}
     }
@@ -4917,7 +4919,7 @@
 		    return NULL;
 		}
 		if (need_type(stack_type, cctx->ctx_ufunc->uf_ret_type, -1,
-						   cctx, FALSE, FALSE) == FAIL)
+						0, cctx, FALSE, FALSE) == FAIL)
 		    return NULL;
 	    }
 	}
@@ -5831,7 +5833,7 @@
 		  : ((type_T **)stack->ga_data)[stack->ga_len - 1];
 	// now we can properly check the type
 	if (lhs->lhs_type->tt_member != NULL && rhs_type != &t_void
-		&& need_type(rhs_type, lhs->lhs_type->tt_member, -2, cctx,
+		&& need_type(rhs_type, lhs->lhs_type->tt_member, -2, 0, cctx,
 							 FALSE, FALSE) == FAIL)
 	    return FAIL;
     }
@@ -5976,7 +5978,7 @@
 		emsg(_(e_cannot_use_void_value));
 		goto theend;
 	    }
-	    if (need_type(stacktype, &t_list_any, -1, cctx,
+	    if (need_type(stacktype, &t_list_any, -1, 0, cctx,
 							 FALSE, FALSE) == FAIL)
 		goto theend;
 	    // TODO: check the length of a constant list here
@@ -6123,13 +6125,13 @@
 			// without operator check type here, otherwise below
 			if (lhs.lhs_has_index)
 			    use_type = lhs.lhs_member_type;
-			if (need_type(rhs_type, use_type, -1, cctx,
+			if (need_type(rhs_type, use_type, -1, 0, cctx,
 						      FALSE, is_const) == FAIL)
 			    goto theend;
 		    }
 		}
 		else if (*p != '=' && need_type(rhs_type, lhs.lhs_member_type,
-					       -1, cctx, FALSE, FALSE) == FAIL)
+					    -1, 0, cctx, FALSE, FALSE) == FAIL)
 		    goto theend;
 	    }
 	    else if (cmdidx == CMD_final)
@@ -6216,7 +6218,7 @@
 		// If variable is float operation with number is OK.
 		!(expected == &t_float && stacktype == &t_number) &&
 #endif
-		    need_type(stacktype, expected, -1, cctx,
+		    need_type(stacktype, expected, -1, 0, cctx,
 							 FALSE, FALSE) == FAIL)
 		goto theend;
 
@@ -6925,7 +6927,7 @@
     // Now that we know the type of "var", check that it is a list, now or at
     // runtime.
     vartype = ((type_T **)stack->ga_data)[stack->ga_len - 1];
-    if (need_type(vartype, &t_list_any, -1, cctx, FALSE, FALSE) == FAIL)
+    if (need_type(vartype, &t_list_any, -1, 0, cctx, FALSE, FALSE) == FAIL)
     {
 	drop_scope(cctx);
 	return NULL;
diff --git a/src/vim9type.c b/src/vim9type.c
index 85f9bd8..81b0db2 100644
--- a/src/vim9type.c
+++ b/src/vim9type.c
@@ -514,25 +514,15 @@
 }
 
 /*
- * Like check_type() but also allow for a runtime type check. E.g. "any" can be
- * used for "number".
- */
-    int
-check_arg_type(type_T *expected, type_T *actual, int argidx)
-{
-    if (check_type(expected, actual, FALSE, 0) == OK
-					    || use_typecheck(actual, expected))
-	return OK;
-    // TODO: should generate a TYPECHECK instruction.
-    return check_type(expected, actual, TRUE, argidx);
-}
-
-/*
  * Check that the arguments of "type" match "argvars[argcount]".
  * Return OK/FAIL.
  */
     int
-check_argument_types(type_T *type, typval_T *argvars, int argcount, char_u *name)
+check_argument_types(
+	type_T	    *type,
+	typval_T    *argvars,
+	int	    argcount,
+	char_u	    *name)
 {
     int	    varargs = (type->tt_flags & TTFLAG_VARARGS) ? 1 : 0;
     int	    i;