diff --git a/crates/ruff/resources/test/fixtures/perflint/PERF401.py b/crates/ruff/resources/test/fixtures/perflint/PERF401.py
index beb3d4546c..12b084e2f6 100644
--- a/crates/ruff/resources/test/fixtures/perflint/PERF401.py
+++ b/crates/ruff/resources/test/fixtures/perflint/PERF401.py
@@ -30,3 +30,10 @@ def f():
     result = []
     for i in items:
         result.append(i)  # OK
+
+
+def f():
+    items = [1, 2, 3, 4]
+    result = {}
+    for i in items:
+        result[i].append(i)  # OK
diff --git a/crates/ruff/resources/test/fixtures/perflint/PERF402.py b/crates/ruff/resources/test/fixtures/perflint/PERF402.py
index 4db9a3dc52..55f3e08cbc 100644
--- a/crates/ruff/resources/test/fixtures/perflint/PERF402.py
+++ b/crates/ruff/resources/test/fixtures/perflint/PERF402.py
@@ -17,3 +17,10 @@ def f():
     result = []
     for i in items:
         result.append(i * i)  # OK
+
+
+def f():
+    items = [1, 2, 3, 4]
+    result = {}
+    for i in items:
+        result[i].append(i * i)  # OK
diff --git a/crates/ruff/src/rules/perflint/rules/manual_list_comprehension.rs b/crates/ruff/src/rules/perflint/rules/manual_list_comprehension.rs
index eb6e56735b..7e9607d591 100644
--- a/crates/ruff/src/rules/perflint/rules/manual_list_comprehension.rs
+++ b/crates/ruff/src/rules/perflint/rules/manual_list_comprehension.rs
@@ -2,6 +2,7 @@ use rustpython_parser::ast::{self, Expr, Stmt};
 
 use ruff_diagnostics::{Diagnostic, Violation};
 use ruff_macros::{derive_message_formats, violation};
+use ruff_python_ast::helpers::any_over_expr;
 
 use crate::checkers::ast::Checker;
 
@@ -52,6 +53,10 @@ impl Violation for ManualListComprehension {
 
 /// PERF401
 pub(crate) fn manual_list_comprehension(checker: &mut Checker, target: &Expr, body: &[Stmt]) {
+    let Expr::Name(ast::ExprName { id, .. }) = target else {
+        return;
+    };
+
     let (stmt, conditional) = match body {
         // ```python
         // for x in y:
@@ -99,22 +104,27 @@ pub(crate) fn manual_list_comprehension(checker: &mut Checker, target: &Expr, bo
 
     // Ignore direct list copies (e.g., `for x in y: filtered.append(x)`).
     if !conditional {
-        if arg.as_name_expr().map_or(false, |arg| {
-            target
-                .as_name_expr()
-                .map_or(false, |target| arg.id == target.id)
-        }) {
+        if arg.as_name_expr().map_or(false, |arg| arg.id == *id) {
             return;
         }
     }
 
-    let Expr::Attribute(ast::ExprAttribute { attr, .. }) = func.as_ref() else {
+    let Expr::Attribute(ast::ExprAttribute { attr, value, .. }) = func.as_ref() else {
         return;
     };
 
-    if attr.as_str() == "append" {
-        checker
-            .diagnostics
-            .push(Diagnostic::new(ManualListComprehension, *range));
+    if attr.as_str() != "append" {
+        return;
     }
+
+    // Avoid, e.g., `for x in y: filtered[x].append(x * x)`.
+    if any_over_expr(value, &|expr| {
+        expr.as_name_expr().map_or(false, |expr| expr.id == *id)
+    }) {
+        return;
+    }
+
+    checker
+        .diagnostics
+        .push(Diagnostic::new(ManualListComprehension, *range));
 }
diff --git a/crates/ruff/src/rules/perflint/rules/manual_list_copy.rs b/crates/ruff/src/rules/perflint/rules/manual_list_copy.rs
index 13554488bd..3752c4eb1c 100644
--- a/crates/ruff/src/rules/perflint/rules/manual_list_copy.rs
+++ b/crates/ruff/src/rules/perflint/rules/manual_list_copy.rs
@@ -2,6 +2,7 @@ use rustpython_parser::ast::{self, Expr, Stmt};
 
 use ruff_diagnostics::{Diagnostic, Violation};
 use ruff_macros::{derive_message_formats, violation};
+use ruff_python_ast::helpers::any_over_expr;
 
 use crate::checkers::ast::Checker;
 
@@ -45,6 +46,10 @@ impl Violation for ManualListCopy {
 
 /// PERF402
 pub(crate) fn manual_list_copy(checker: &mut Checker, target: &Expr, body: &[Stmt]) {
+    let Expr::Name(ast::ExprName { id, .. }) = target else {
+        return;
+    };
+
     let [stmt] = body else {
         return;
     };
@@ -72,21 +77,26 @@ pub(crate) fn manual_list_copy(checker: &mut Checker, target: &Expr, body: &[Stm
     };
 
     // Only flag direct list copies (e.g., `for x in y: filtered.append(x)`).
-    if !arg.as_name_expr().map_or(false, |arg| {
-        target
-            .as_name_expr()
-            .map_or(false, |target| arg.id == target.id)
+    if !arg.as_name_expr().map_or(false, |arg| arg.id == *id) {
+        return;
+    }
+
+    let Expr::Attribute(ast::ExprAttribute { attr, value, .. }) = func.as_ref() else {
+        return;
+    };
+
+    if !matches!(attr.as_str(), "append" | "insert") {
+        return;
+    }
+
+    // Avoid, e.g., `for x in y: filtered[x].append(x * x)`.
+    if any_over_expr(value, &|expr| {
+        expr.as_name_expr().map_or(false, |expr| expr.id == *id)
     }) {
         return;
     }
 
-    let Expr::Attribute(ast::ExprAttribute { attr, .. }) = func.as_ref() else {
-        return;
-    };
-
-    if matches!(attr.as_str(), "append" | "insert") {
-        checker
-            .diagnostics
-            .push(Diagnostic::new(ManualListCopy, *range));
-    }
+    checker
+        .diagnostics
+        .push(Diagnostic::new(ManualListCopy, *range));
 }