diff --git a/clippy_lints/src/suspicious_trait_impl.rs b/clippy_lints/src/suspicious_trait_impl.rs
index 89b57ed1a8de..8189fc239b5d 100644
--- a/clippy_lints/src/suspicious_trait_impl.rs
+++ b/clippy_lints/src/suspicious_trait_impl.rs
@@ -72,7 +72,8 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for SuspiciousImpl {
                     match e.kind {
                         hir::ExprKind::Binary(..)
                         | hir::ExprKind::Unary(hir::UnOp::UnNot, _)
-                        | hir::ExprKind::Unary(hir::UnOp::UnNeg, _) => return,
+                        | hir::ExprKind::Unary(hir::UnOp::UnNeg, _)
+                        | hir::ExprKind::AssignOp(..) => return,
                         _ => {},
                     }
                 }
diff --git a/tests/ui/suspicious_arithmetic_impl.rs b/tests/ui/suspicious_arithmetic_impl.rs
index 6ee924d3b2ed..be6e42d57450 100644
--- a/tests/ui/suspicious_arithmetic_impl.rs
+++ b/tests/ui/suspicious_arithmetic_impl.rs
@@ -1,5 +1,5 @@
 #![warn(clippy::suspicious_arithmetic_impl)]
-use std::ops::{Add, AddAssign, Div, Mul, Sub};
+use std::ops::{Add, AddAssign, Div, Mul, Sub, BitOrAssign};
 
 #[derive(Copy, Clone)]
 struct Foo(u32);
@@ -18,6 +18,13 @@ impl AddAssign for Foo {
     }
 }
 
+impl BitOrAssign for Foo {
+    fn bitor_assign(&mut self, other: Foo) {
+        let idx = other.0;
+        self.0 |= 1 << idx;
+    }
+}
+
 impl Mul for Foo {
     type Output = Foo;