diff --git a/pykwasm/src/pykwasm/kwasm_ast.py b/pykwasm/src/pykwasm/kwasm_ast.py
index 0dc74ace9..0471e06de 100644
--- a/pykwasm/src/pykwasm/kwasm_ast.py
+++ b/pykwasm/src/pykwasm/kwasm_ast.py
@@ -246,8 +246,8 @@ def CALL_INDIRECT(type_idx: int) -> KInner:
 I32_EXTEND8_s = KApply('aExtendS', [i32, KApply('aExtend8_s', [])])
 I32_EXTEND16_s = KApply('aExtendS', [i32, KApply('aExtend16_s', [])])
 I64_EXTEND8_s = KApply('aExtendS', [i32, KApply('aExtend8_s', [])])
-I64_EXTEND8_s = KApply('aExtendS', [i32, KApply('aExtend16_s', [])])
-I64_EXTEND8_s = KApply('aExtendS', [i32, KApply('aExtend32_s', [])])
+I64_EXTEND16_s = KApply('aExtendS', [i32, KApply('aExtend16_s', [])])
+I64_EXTEND32_s = KApply('aExtendS', [i32, KApply('aExtend32_s', [])])
 
 ###############
 # Float BinOp #
diff --git a/pykwasm/src/tests/integration/binary/instrs.wat b/pykwasm/src/tests/integration/binary/instrs.wat
index e86b313d0..22aebf8ab 100644
--- a/pykwasm/src/tests/integration/binary/instrs.wat
+++ b/pykwasm/src/tests/integration/binary/instrs.wat
@@ -13,9 +13,11 @@
         ;; Commented out instructions are not currently supported by py-wasm.
         i32.const 0                   drop
         f32.const 0                   drop
-     ;; i32.extend8_s                 drop
-     ;; i32.extend16_s                drop
-     ;; i64.extend32_s                drop
+        i32.extend8_s                 drop
+        i32.extend16_s                drop
+        i64.extend8_s                 drop
+        i64.extend16_s                drop
+        i64.extend32_s                drop
         i32.wrap_i64                  drop
         i64.extend_i32_s              drop
         i64.extend_i32_u              drop