diff --git a/core/prelude/i32.carbon b/core/prelude/i32.carbon
index 6b3068e8bac0..365e5e310131 100644
--- a/core/prelude/i32.carbon
+++ b/core/prelude/i32.carbon
@@ -25,7 +25,7 @@ impl i32 as BitAnd {
 }
 impl i32 as BitAndAssign {
   fn Op[addr self: Self*](other: Self) {
-    *self = *self + other;
+    *self = *self & other;
   }
 }
 
@@ -38,7 +38,7 @@ impl i32 as BitOr {
 }
 impl i32 as BitOrAssign {
   fn Op[addr self: Self*](other: Self) {
-    *self = *self + other;
+    *self = *self | other;
   }
 }
 
diff --git a/examples/sieve.carbon b/examples/sieve.carbon
index 18eba08ccdd5..921961f22daa 100644
--- a/examples/sieve.carbon
+++ b/examples/sieve.carbon
@@ -29,7 +29,7 @@ impl i32 as Core.BitAnd {
 }
 impl i32 as Core.BitAndAssign {
   fn Op[addr self: Self*](other: Self) {
-    *self = *self + other;
+    *self = *self & other;
   }
 }
 
@@ -42,7 +42,7 @@ impl i32 as Core.BitOr {
 }
 impl i32 as Core.BitOrAssign {
   fn Op[addr self: Self*](other: Self) {
-    *self = *self + other;
+    *self = *self | other;
   }
 }