diff --git a/crates/red_knot_python_semantic/resources/mdtest/assignment/augmented.md b/crates/red_knot_python_semantic/resources/mdtest/assignment/augmented.md
index 316d5bdfda..fb202c0ab9 100644
--- a/crates/red_knot_python_semantic/resources/mdtest/assignment/augmented.md
+++ b/crates/red_knot_python_semantic/resources/mdtest/assignment/augmented.md
@@ -6,6 +6,10 @@
 x = 3
 x -= 1
 reveal_type(x)  # revealed: Literal[2]
+
+x = 1.0
+x /= 2
+reveal_type(x)  # revealed: float
 ```
 
 ## Dunder methods
diff --git a/crates/red_knot_python_semantic/src/types/infer.rs b/crates/red_knot_python_semantic/src/types/infer.rs
index c987028c90..a8d5e500c3 100644
--- a/crates/red_knot_python_semantic/src/types/infer.rs
+++ b/crates/red_knot_python_semantic/src/types/infer.rs
@@ -1425,26 +1425,32 @@ impl<'db> TypeInferenceBuilder<'db> {
         };
         let value_type = self.infer_expression(value);
 
+        // If the target defines, e.g., `__iadd__`, infer the augmented assignment as a call to that
+        // dunder.
         if let Type::Instance(class) = target_type {
             let class_member = class.class_member(self.db, op.in_place_dunder());
-            let call = class_member.call(self.db, &[target_type, value_type]);
-
-            return match call.return_ty_result(self.db, AnyNodeRef::StmtAugAssign(assignment), self)
-            {
-                Ok(t) => t,
-                Err(e) => {
-                    self.add_diagnostic(
-                        assignment.into(),
-                        "unsupported-operator",
-                        format_args!(
-                            "Operator `{op}=` is unsupported between objects of type `{}` and `{}`",
-                            target_type.display(self.db),
-                            value_type.display(self.db)
-                        ),
-                    );
-                    e.return_ty()
-                }
-            };
+            if !class_member.is_unbound() {
+                let call = class_member.call(self.db, &[target_type, value_type]);
+                return match call.return_ty_result(
+                    self.db,
+                    AnyNodeRef::StmtAugAssign(assignment),
+                    self,
+                ) {
+                    Ok(t) => t,
+                    Err(e) => {
+                        self.add_diagnostic(
+                            assignment.into(),
+                            "unsupported-operator",
+                            format_args!(
+                                "Operator `{op}=` is unsupported between objects of type `{}` and `{}`",
+                                target_type.display(self.db),
+                                value_type.display(self.db)
+                            ),
+                        );
+                        e.return_ty()
+                    }
+                };
+            }
         }
 
         let left_ty = target_type;
diff --git a/crates/ruff_benchmark/benches/red_knot.rs b/crates/ruff_benchmark/benches/red_knot.rs
index b059df6af7..6e52ccc409 100644
--- a/crates/ruff_benchmark/benches/red_knot.rs
+++ b/crates/ruff_benchmark/benches/red_knot.rs
@@ -28,30 +28,22 @@ static EXPECTED_DIAGNOSTICS: &[&str] = &[
     // We don't support terminal statements in control flow yet:
     "/src/tomllib/_parser.py:66:18: Name `s` used when possibly not defined",
     "/src/tomllib/_parser.py:98:12: Name `char` used when possibly not defined",
-    "/src/tomllib/_parser.py:99:13: Operator `+=` is unsupported for type `int` with type `Literal[1]`",
     "/src/tomllib/_parser.py:101:12: Name `char` used when possibly not defined",
     "/src/tomllib/_parser.py:104:14: Name `char` used when possibly not defined",
     "/src/tomllib/_parser.py:108:17: Conflicting declared types for `second_char`: Unknown, str | None",
     "/src/tomllib/_parser.py:115:14: Name `char` used when possibly not defined",
     "/src/tomllib/_parser.py:126:12: Name `char` used when possibly not defined",
-    "/src/tomllib/_parser.py:130:9: Operator `+=` is unsupported for type `int` with type `Literal[1]`",
     "/src/tomllib/_parser.py:267:9: Conflicting declared types for `char`: Unknown, str | None",
     "/src/tomllib/_parser.py:348:20: Name `nest` used when possibly not defined",
     "/src/tomllib/_parser.py:353:5: Name `nest` used when possibly not defined",
     "/src/tomllib/_parser.py:353:5: Method `__getitem__` of type `Unbound | @Todo` is not callable on object of type `Unbound | @Todo`",
     "/src/tomllib/_parser.py:364:9: Conflicting declared types for `char`: Unknown, str | None",
-    "/src/tomllib/_parser.py:367:5: Operator `+=` is unsupported for type `int` with type `Literal[1]`",
     "/src/tomllib/_parser.py:381:13: Conflicting declared types for `char`: Unknown, str | None",
-    "/src/tomllib/_parser.py:384:9: Operator `+=` is unsupported for type `int` with type `Literal[1]`",
     "/src/tomllib/_parser.py:395:9: Conflicting declared types for `char`: Unknown, str | None",
-    "/src/tomllib/_parser.py:429:9: Operator `+=` is unsupported for type `int` with type `Literal[1]`",
     "/src/tomllib/_parser.py:453:24: Name `nest` used when possibly not defined",
     "/src/tomllib/_parser.py:455:9: Name `nest` used when possibly not defined",
     "/src/tomllib/_parser.py:455:9: Method `__getitem__` of type `Unbound | @Todo` is not callable on object of type `Unbound | @Todo`",
-    "/src/tomllib/_parser.py:464:9: Operator `+=` is unsupported for type `int` with type `Literal[1]`",
     "/src/tomllib/_parser.py:482:16: Name `char` used when possibly not defined",
-    "/src/tomllib/_parser.py:484:13: Operator `+=` is unsupported for type `int` with type `Literal[1]`",
-    "/src/tomllib/_parser.py:545:5: Operator `+=` is unsupported for type `int` with type `Literal[1]`",
     "/src/tomllib/_parser.py:566:12: Name `char` used when possibly not defined",
     "/src/tomllib/_parser.py:573:12: Name `char` used when possibly not defined",
     "/src/tomllib/_parser.py:579:12: Name `char` used when possibly not defined",