diff --git a/prism/config.yml b/prism/config.yml
index 7e71e4e50b3775..d3b6b08709c492 100644
--- a/prism/config.yml
+++ b/prism/config.yml
@@ -345,6 +345,8 @@ flags:
         comment: "&. operator"
       - name: VARIABLE_CALL
         comment: "a call that could have been a local variable"
+      - name: ATTRIBUTE_WRITE
+        comment: "a call that is an attribute write, so the value being written should be returned"
     comment: Flags for call nodes.
   - name: EncodingFlags
     values:
diff --git a/prism/prism.c b/prism/prism.c
index 1474a1854f49ed..2b74152cce1884 100644
--- a/prism/prism.c
+++ b/prism/prism.c
@@ -10856,6 +10856,7 @@ parse_write(pm_parser_t *parser, pm_node_t *target, pm_token_t *operator, pm_nod
                     call->base.location.end = arguments->base.location.end;
 
                     parse_write_name(parser, &call->name);
+                    call->base.flags |= PM_CALL_NODE_FLAGS_ATTRIBUTE_WRITE;
                     return (pm_node_t *) call;
                 }
             }
@@ -10873,6 +10874,7 @@ parse_write(pm_parser_t *parser, pm_node_t *target, pm_token_t *operator, pm_nod
 
                 // Replace the name with "[]=".
                 call->name = pm_parser_constant_id_constant(parser, "[]=", 3);
+                call->base.flags |= PM_CALL_NODE_FLAGS_ATTRIBUTE_WRITE;
                 return target;
             }
 
diff --git a/test/prism/attribute_write_test.rb b/test/prism/attribute_write_test.rb
new file mode 100644
index 00000000000000..bd83d72da35591
--- /dev/null
+++ b/test/prism/attribute_write_test.rb
@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+require_relative "test_helper"
+
+module Prism
+  class AttributeWriteTest < TestCase
+    module Target
+      def self.value
+        2
+      end
+
+      def self.value=(value)
+        2
+      end
+
+      def self.[]=(index, value)
+        2
+      end
+    end
+
+    def test_named_call_with_operator
+      assert_attribute_write("Target.value = 1")
+    end
+
+    def test_named_call_without_operator
+      assert_attribute_write("Target.value=(1)")
+    end
+
+    def test_indexed_call_with_operator
+      assert_attribute_write("Target[0] = 1")
+    end
+
+    def test_indexed_call_without_operator
+      refute_attribute_write("Target.[]=(0, 1)")
+    end
+
+    def test_comparison_operators
+      refute_attribute_write("Target.value == 1")
+      refute_attribute_write("Target.value === 1")
+    end
+
+    private
+
+    def parse(source)
+      Prism.parse(source).value.statements.body.first
+    end
+
+    def assert_attribute_write(source)
+      call = parse(source)
+      assert(call.attribute_write?)
+      assert_equal(1, eval(source))
+    end
+
+    def refute_attribute_write(source)
+      call = parse(source)
+      refute(call.attribute_write?)
+      refute_equal(1, eval(source))
+    end
+  end
+end
diff --git a/test/prism/snapshots/arrays.txt b/test/prism/snapshots/arrays.txt
index 7601fc38d9526d..d31cd7afc857a7 100644
--- a/test/prism/snapshots/arrays.txt
+++ b/test/prism/snapshots/arrays.txt
@@ -22,7 +22,7 @@
         │   ├── opening_loc: (1,0)-(1,1) = "["
         │   └── closing_loc: (1,3)-(1,4) = "]"
         ├── @ CallNode (location: (3,0)-(3,23))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ CallNode (location: (3,0)-(3,3))
         │   │   ├── flags: variable_call
@@ -205,7 +205,7 @@
         │   ├── opening_loc: (28,0)-(28,1) = "["
         │   └── closing_loc: (28,11)-(28,12) = "]"
         ├── @ CallNode (location: (30,0)-(30,19))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ CallNode (location: (30,0)-(30,8))
         │   │   ├── flags: ∅
@@ -375,7 +375,7 @@
         │   ├── closing_loc: (37,12)-(37,13) = "]"
         │   └── block: ∅
         ├── @ CallNode (location: (39,0)-(39,19))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ CallNode (location: (39,0)-(39,3))
         │   │   ├── flags: variable_call
@@ -510,7 +510,7 @@
         │   │   ├── flags: ∅
         │   │   └── arguments: (length: 1)
         │   │       └── @ CallNode (location: (43,4)-(43,18))
-        │   │           ├── flags: ∅
+        │   │           ├── flags: attribute_write
         │   │           ├── receiver:
         │   │           │   @ CallNode (location: (43,4)-(43,7))
         │   │           │   ├── flags: variable_call
@@ -588,7 +588,7 @@
         │   ├── closing_loc: (45,7)-(45,8) = "]"
         │   └── block: ∅
         ├── @ CallNode (location: (47,0)-(47,14))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ CallNode (location: (47,0)-(47,3))
         │   │   ├── flags: variable_call
@@ -932,7 +932,7 @@
         │   ├── opening_loc: (82,0)-(82,3) = "%w["
         │   └── closing_loc: (82,6)-(82,7) = "]"
         ├── @ CallNode (location: (84,0)-(84,13))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ CallNode (location: (84,0)-(84,3))
         │   │   ├── flags: variable_call
@@ -970,7 +970,7 @@
         │       │   └── block: ∅
         │       └── operator_loc: (84,4)-(84,5) = "&"
         ├── @ CallNode (location: (86,0)-(86,17))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ CallNode (location: (86,0)-(86,7))
         │   │   ├── flags: ∅
@@ -1038,7 +1038,7 @@
         │   │   @ StatementsNode (location: (89,2)-(89,12))
         │   │   └── body: (length: 1)
         │   │       └── @ CallNode (location: (89,2)-(89,12))
-        │   │           ├── flags: ∅
+        │   │           ├── flags: attribute_write
         │   │           ├── receiver:
         │   │           │   @ CallNode (location: (89,2)-(89,5))
         │   │           │   ├── flags: variable_call
@@ -1930,7 +1930,7 @@
         │   │   @ StatementsNode (location: (132,10)-(132,18))
         │   │   └── body: (length: 1)
         │   │       └── @ CallNode (location: (132,10)-(132,18))
-        │   │           ├── flags: ∅
+        │   │           ├── flags: attribute_write
         │   │           ├── receiver:
         │   │           │   @ CallNode (location: (132,10)-(132,11))
         │   │           │   ├── flags: variable_call
@@ -1986,7 +1986,7 @@
         │   │   @ StatementsNode (location: (134,10)-(134,21))
         │   │   └── body: (length: 1)
         │   │       └── @ CallNode (location: (134,10)-(134,21))
-        │   │           ├── flags: ∅
+        │   │           ├── flags: attribute_write
         │   │           ├── receiver:
         │   │           │   @ CallNode (location: (134,10)-(134,11))
         │   │           │   ├── flags: variable_call
diff --git a/test/prism/snapshots/method_calls.txt b/test/prism/snapshots/method_calls.txt
index 772d4cadbfc53d..65f0d1df165adb 100644
--- a/test/prism/snapshots/method_calls.txt
+++ b/test/prism/snapshots/method_calls.txt
@@ -238,7 +238,7 @@
         │   ├── closing_loc: ∅
         │   └── block: ∅
         ├── @ CallNode (location: (21,0)-(21,11))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ CallNode (location: (21,0)-(21,3))
         │   │   ├── flags: variable_call
diff --git a/test/prism/snapshots/seattlerb/attr_asgn_colon_id.txt b/test/prism/snapshots/seattlerb/attr_asgn_colon_id.txt
index c8478c368bb70b..c869af46072bb0 100644
--- a/test/prism/snapshots/seattlerb/attr_asgn_colon_id.txt
+++ b/test/prism/snapshots/seattlerb/attr_asgn_colon_id.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(1,8))
     └── body: (length: 1)
         └── @ CallNode (location: (1,0)-(1,8))
-            ├── flags: ∅
+            ├── flags: attribute_write
             ├── receiver:
             │   @ ConstantReadNode (location: (1,0)-(1,1))
             │   └── name: :A
diff --git a/test/prism/snapshots/seattlerb/attrasgn_array_arg.txt b/test/prism/snapshots/seattlerb/attrasgn_array_arg.txt
index 3b09e172e76cf2..d9e557229210f4 100644
--- a/test/prism/snapshots/seattlerb/attrasgn_array_arg.txt
+++ b/test/prism/snapshots/seattlerb/attrasgn_array_arg.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(1,13))
     └── body: (length: 1)
         └── @ CallNode (location: (1,0)-(1,13))
-            ├── flags: ∅
+            ├── flags: attribute_write
             ├── receiver:
             │   @ CallNode (location: (1,0)-(1,1))
             │   ├── flags: variable_call
diff --git a/test/prism/snapshots/seattlerb/attrasgn_array_lhs.txt b/test/prism/snapshots/seattlerb/attrasgn_array_lhs.txt
index 13615477dfcc69..9a41409dbb0a03 100644
--- a/test/prism/snapshots/seattlerb/attrasgn_array_lhs.txt
+++ b/test/prism/snapshots/seattlerb/attrasgn_array_lhs.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(1,42))
     └── body: (length: 1)
         └── @ CallNode (location: (1,0)-(1,42))
-            ├── flags: ∅
+            ├── flags: attribute_write
             ├── receiver:
             │   @ ArrayNode (location: (1,0)-(1,12))
             │   ├── flags: ∅
diff --git a/test/prism/snapshots/seattlerb/attrasgn_primary_dot_constant.txt b/test/prism/snapshots/seattlerb/attrasgn_primary_dot_constant.txt
index 4f22f3380a42e6..74faad33032cf3 100644
--- a/test/prism/snapshots/seattlerb/attrasgn_primary_dot_constant.txt
+++ b/test/prism/snapshots/seattlerb/attrasgn_primary_dot_constant.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(1,7))
     └── body: (length: 1)
         └── @ CallNode (location: (1,0)-(1,7))
-            ├── flags: ∅
+            ├── flags: attribute_write
             ├── receiver:
             │   @ CallNode (location: (1,0)-(1,1))
             │   ├── flags: variable_call
diff --git a/test/prism/snapshots/seattlerb/eq_begin_why_wont_people_use_their_spacebar.txt b/test/prism/snapshots/seattlerb/eq_begin_why_wont_people_use_their_spacebar.txt
index 3b53fee11e9f01..545f29a5324bf2 100644
--- a/test/prism/snapshots/seattlerb/eq_begin_why_wont_people_use_their_spacebar.txt
+++ b/test/prism/snapshots/seattlerb/eq_begin_why_wont_people_use_their_spacebar.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(3,8))
     └── body: (length: 1)
         └── @ CallNode (location: (1,0)-(3,8))
-            ├── flags: ∅
+            ├── flags: attribute_write
             ├── receiver:
             │   @ CallNode (location: (1,0)-(1,1))
             │   ├── flags: variable_call
diff --git a/test/prism/snapshots/seattlerb/index_0.txt b/test/prism/snapshots/seattlerb/index_0.txt
index 3be81b5435da6c..38a7d5d5c9cd22 100644
--- a/test/prism/snapshots/seattlerb/index_0.txt
+++ b/test/prism/snapshots/seattlerb/index_0.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(1,7))
     └── body: (length: 1)
         └── @ CallNode (location: (1,0)-(1,7))
-            ├── flags: ∅
+            ├── flags: attribute_write
             ├── receiver:
             │   @ CallNode (location: (1,0)-(1,1))
             │   ├── flags: variable_call
diff --git a/test/prism/snapshots/seattlerb/safe_attrasgn.txt b/test/prism/snapshots/seattlerb/safe_attrasgn.txt
index b29fef3febeb78..530ae743627e39 100644
--- a/test/prism/snapshots/seattlerb/safe_attrasgn.txt
+++ b/test/prism/snapshots/seattlerb/safe_attrasgn.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(1,8))
     └── body: (length: 1)
         └── @ CallNode (location: (1,0)-(1,8))
-            ├── flags: safe_navigation
+            ├── flags: safe_navigation, attribute_write
             ├── receiver:
             │   @ CallNode (location: (1,0)-(1,1))
             │   ├── flags: variable_call
diff --git a/test/prism/snapshots/seattlerb/safe_attrasgn_constant.txt b/test/prism/snapshots/seattlerb/safe_attrasgn_constant.txt
index 39fb489e5eb3fe..c34b981d9d9d67 100644
--- a/test/prism/snapshots/seattlerb/safe_attrasgn_constant.txt
+++ b/test/prism/snapshots/seattlerb/safe_attrasgn_constant.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(1,8))
     └── body: (length: 1)
         └── @ CallNode (location: (1,0)-(1,8))
-            ├── flags: safe_navigation
+            ├── flags: safe_navigation, attribute_write
             ├── receiver:
             │   @ CallNode (location: (1,0)-(1,1))
             │   ├── flags: variable_call
diff --git a/test/prism/snapshots/unparser/corpus/literal/assignment.txt b/test/prism/snapshots/unparser/corpus/literal/assignment.txt
index 7855e269743ba1..18edafe4153884 100644
--- a/test/prism/snapshots/unparser/corpus/literal/assignment.txt
+++ b/test/prism/snapshots/unparser/corpus/literal/assignment.txt
@@ -596,7 +596,7 @@
         │   ├── closing_loc: ∅
         │   └── block: ∅
         ├── @ CallNode (location: (29,0)-(29,19))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ LocalVariableReadNode (location: (29,0)-(29,3))
         │   │   ├── name: :foo
@@ -635,7 +635,7 @@
         │   ├── closing_loc: (29,10)-(29,11) = "]"
         │   └── block: ∅
         ├── @ CallNode (location: (30,0)-(30,17))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ LocalVariableReadNode (location: (30,0)-(30,3))
         │   │   ├── name: :foo
@@ -670,7 +670,7 @@
         │   ├── closing_loc: (30,8)-(30,9) = "]"
         │   └── block: ∅
         ├── @ CallNode (location: (31,0)-(31,9))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ LocalVariableReadNode (location: (31,0)-(31,3))
         │   │   ├── name: :foo
@@ -688,7 +688,7 @@
         │   ├── closing_loc: (31,4)-(31,5) = "]"
         │   └── block: ∅
         ├── @ CallNode (location: (32,0)-(32,17))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ LocalVariableReadNode (location: (32,0)-(32,3))
         │   │   ├── name: :foo
@@ -720,7 +720,7 @@
         │   ├── closing_loc: (32,8)-(32,9) = "]"
         │   └── block: ∅
         ├── @ CallNode (location: (33,0)-(33,18))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ LocalVariableReadNode (location: (33,0)-(33,3))
         │   │   ├── name: :foo
@@ -768,7 +768,7 @@
         │   │   └── unescaped: ""
         │   └── operator_loc: (34,2)-(34,3) = "="
         ├── @ CallNode (location: (35,0)-(35,7))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ LocalVariableReadNode (location: (35,0)-(35,1))
         │   │   ├── name: :x
@@ -790,7 +790,7 @@
         │   ├── closing_loc: ∅
         │   └── block: ∅
         ├── @ CallNode (location: (36,0)-(36,12))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ LocalVariableReadNode (location: (36,0)-(36,1))
         │   │   ├── name: :x
@@ -891,7 +891,7 @@
         │   │   └── closing_loc: (41,0)-(42,0) = "HEREDOC\n"
         │   └── operator_loc: (39,2)-(39,3) = "="
         ├── @ CallNode (location: (42,0)-(42,14))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ LocalVariableReadNode (location: (42,0)-(42,1))
         │   │   ├── name: :x
@@ -927,7 +927,7 @@
         │   ├── closing_loc: ∅
         │   └── block: ∅
         ├── @ CallNode (location: (45,0)-(45,16))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ LocalVariableReadNode (location: (45,0)-(45,1))
         │   │   ├── name: :x
diff --git a/test/prism/snapshots/unparser/corpus/literal/case.txt b/test/prism/snapshots/unparser/corpus/literal/case.txt
index a228c4af407f57..be095579560e79 100644
--- a/test/prism/snapshots/unparser/corpus/literal/case.txt
+++ b/test/prism/snapshots/unparser/corpus/literal/case.txt
@@ -404,7 +404,7 @@
             │       │       ├── operator_loc: (36,5)-(36,6) = "*"
             │       │       └── expression:
             │       │           @ CallNode (location: (36,6)-(36,15))
-            │       │           ├── flags: ∅
+            │       │           ├── flags: attribute_write
             │       │           ├── receiver:
             │       │           │   @ CallNode (location: (36,6)-(36,9))
             │       │           │   ├── flags: variable_call
diff --git a/test/prism/snapshots/unparser/corpus/literal/opasgn.txt b/test/prism/snapshots/unparser/corpus/literal/opasgn.txt
index 764ae3adc2f1b9..cf7de993c1caaf 100644
--- a/test/prism/snapshots/unparser/corpus/literal/opasgn.txt
+++ b/test/prism/snapshots/unparser/corpus/literal/opasgn.txt
@@ -97,7 +97,7 @@
         │   ├── closing_loc: ∅
         │   └── block: ∅
         ├── @ CallNode (location: (9,0)-(9,17))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ ParenthesesNode (location: (9,0)-(9,10))
         │   │   ├── body:
diff --git a/test/prism/snapshots/unparser/corpus/literal/send.txt b/test/prism/snapshots/unparser/corpus/literal/send.txt
index e0e27bc522aa2f..a96937e87ee7e6 100644
--- a/test/prism/snapshots/unparser/corpus/literal/send.txt
+++ b/test/prism/snapshots/unparser/corpus/literal/send.txt
@@ -1529,7 +1529,7 @@
         │   ├── closing_loc: (68,25)-(68,26) = ")"
         │   └── block: ∅
         ├── @ CallNode (location: (69,0)-(69,12))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ CallNode (location: (69,0)-(69,3))
         │   │   ├── flags: variable_call
@@ -1773,7 +1773,7 @@
         │   ├── closing_loc: ∅
         │   └── block: ∅
         ├── @ CallNode (location: (77,0)-(77,13))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ SelfNode (location: (77,0)-(77,4))
         │   ├── call_operator_loc: (77,4)-(77,5) = "."
diff --git a/test/prism/snapshots/whitequark/send_attr_asgn.txt b/test/prism/snapshots/whitequark/send_attr_asgn.txt
index 948e52808b8b53..938fcf7541c8e6 100644
--- a/test/prism/snapshots/whitequark/send_attr_asgn.txt
+++ b/test/prism/snapshots/whitequark/send_attr_asgn.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(7,10))
     └── body: (length: 4)
         ├── @ CallNode (location: (1,0)-(1,9))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ CallNode (location: (1,0)-(1,3))
         │   │   ├── flags: variable_call
@@ -29,7 +29,7 @@
         │   ├── closing_loc: ∅
         │   └── block: ∅
         ├── @ CallNode (location: (3,0)-(3,9))
-        │   ├── flags: ∅
+        │   ├── flags: attribute_write
         │   ├── receiver:
         │   │   @ CallNode (location: (3,0)-(3,3))
         │   │   ├── flags: variable_call
@@ -76,7 +76,7 @@
         │       @ IntegerNode (location: (5,9)-(5,10))
         │       └── flags: decimal
         └── @ CallNode (location: (7,0)-(7,10))
-            ├── flags: ∅
+            ├── flags: attribute_write
             ├── receiver:
             │   @ CallNode (location: (7,0)-(7,3))
             │   ├── flags: variable_call
diff --git a/test/prism/snapshots/whitequark/send_attr_asgn_conditional.txt b/test/prism/snapshots/whitequark/send_attr_asgn_conditional.txt
index b29fef3febeb78..530ae743627e39 100644
--- a/test/prism/snapshots/whitequark/send_attr_asgn_conditional.txt
+++ b/test/prism/snapshots/whitequark/send_attr_asgn_conditional.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(1,8))
     └── body: (length: 1)
         └── @ CallNode (location: (1,0)-(1,8))
-            ├── flags: safe_navigation
+            ├── flags: safe_navigation, attribute_write
             ├── receiver:
             │   @ CallNode (location: (1,0)-(1,1))
             │   ├── flags: variable_call
diff --git a/test/prism/snapshots/whitequark/send_index_asgn.txt b/test/prism/snapshots/whitequark/send_index_asgn.txt
index 3f550ea420ab22..34adbb1dde66c3 100644
--- a/test/prism/snapshots/whitequark/send_index_asgn.txt
+++ b/test/prism/snapshots/whitequark/send_index_asgn.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(1,13))
     └── body: (length: 1)
         └── @ CallNode (location: (1,0)-(1,13))
-            ├── flags: ∅
+            ├── flags: attribute_write
             ├── receiver:
             │   @ CallNode (location: (1,0)-(1,3))
             │   ├── flags: variable_call
diff --git a/test/prism/snapshots/whitequark/send_index_asgn_legacy.txt b/test/prism/snapshots/whitequark/send_index_asgn_legacy.txt
index 3f550ea420ab22..34adbb1dde66c3 100644
--- a/test/prism/snapshots/whitequark/send_index_asgn_legacy.txt
+++ b/test/prism/snapshots/whitequark/send_index_asgn_legacy.txt
@@ -4,7 +4,7 @@
     @ StatementsNode (location: (1,0)-(1,13))
     └── body: (length: 1)
         └── @ CallNode (location: (1,0)-(1,13))
-            ├── flags: ∅
+            ├── flags: attribute_write
             ├── receiver:
             │   @ CallNode (location: (1,0)-(1,3))
             │   ├── flags: variable_call