diff --git a/librz/il/il_export.c b/librz/il/il_export.c
index d3b6602dae..bc6a91bd6b 100644
--- a/librz/il/il_export.c
+++ b/librz/il/il_export.c
@@ -335,7 +335,7 @@ static void il_opdmp_concat(RzILOpPure *op, RzStrBuf *sb, PJ *pj) {
 }
 
 static void il_opdmp_append(RzILOpPure *op, RzStrBuf *sb, PJ *pj) {
-	il_op_param_2("append", op->op.append, pure, x, pure, y);
+	il_op_param_2("append", op->op.append, pure, high, pure, low);
 }
 
 static void il_opdmp_load(RzILOpPure *op, RzStrBuf *sb, PJ *pj) {
diff --git a/librz/il/il_opcodes.c b/librz/il/il_opcodes.c
index 83623ea543..dc875683cd 100644
--- a/librz/il/il_opcodes.c
+++ b/librz/il/il_opcodes.c
@@ -477,12 +477,12 @@ RZ_API RZ_OWN RzILOpBitVector *rz_il_op_new_shiftr(RZ_NONNULL RzILOpBool *fill_b
 }
 
 /**
- *  \brief op structure for appending 2 bitv: MSB:LSB y:x
+ *  \brief op structure for appending 2 bitv: MSB:LSB high:low
  */
-RZ_API RZ_OWN RzILOpBitVector *rz_il_op_new_append(RZ_NONNULL RzILOpBitVector *x, RZ_NONNULL RzILOpBitVector *y) {
-	rz_return_val_if_fail(x && y, NULL);
+RZ_API RZ_OWN RzILOpBitVector *rz_il_op_new_append(RZ_NONNULL RzILOpBitVector *high, RZ_NONNULL RzILOpBitVector *low) {
+	rz_return_val_if_fail(high && low, NULL);
 	RzILOpBitVector *ret;
-	rz_il_op_new_2(BitVector, RZ_IL_OP_APPEND, RzILOpArgsAppend, append, x, y);
+	rz_il_op_new_2(BitVector, RZ_IL_OP_APPEND, RzILOpArgsAppend, append, high, low);
 	return ret;
 }
 
@@ -828,7 +828,7 @@ RZ_API RzILOpPure *rz_il_op_pure_dup(RZ_NONNULL RzILOpPure *op) {
 		rz_warn_if_reached();
 		break;
 	case RZ_IL_OP_APPEND:
-		DUP_OP2(append, x, y);
+		DUP_OP2(append, high, low);
 		break;
 	case RZ_IL_OP_LOAD:
 		r->op.load.mem = op->op.load.mem;
@@ -955,7 +955,7 @@ RZ_API void rz_il_op_pure_free(RZ_NULLABLE RzILOpPure *op) {
 		rz_warn_if_reached();
 		break;
 	case RZ_IL_OP_APPEND:
-		rz_il_op_free_2(pure, append, x, y);
+		rz_il_op_free_2(pure, append, high, low);
 		break;
 	case RZ_IL_OP_LOAD:
 		rz_il_op_free_1(pure, load, key);
diff --git a/librz/il/theory_bitv.c b/librz/il/theory_bitv.c
index b71e70eb19..788015cb14 100644
--- a/librz/il/theory_bitv.c
+++ b/librz/il/theory_bitv.c
@@ -132,11 +132,11 @@ void *rz_il_handler_append(RzILVM *vm, RzILOpBitVector *op, RzILPureType *type)
 
 	RzILOpArgsAppend *op_append = &op->op.append;
 
-	RzBitVector *x = rz_il_evaluate_bitv(vm, op_append->x);
-	RzBitVector *y = rz_il_evaluate_bitv(vm, op_append->y);
-	RzBitVector *result = x && y ? rz_bv_append(x, y) : NULL;
-	rz_bv_free(x);
-	rz_bv_free(y);
+	RzBitVector *high = rz_il_evaluate_bitv(vm, op_append->high);
+	RzBitVector *low = rz_il_evaluate_bitv(vm, op_append->low);
+	RzBitVector *result = high && low ? rz_bv_append(high, low) : NULL;
+	rz_bv_free(low);
+	rz_bv_free(high);
 
 	*type = RZ_IL_PURE_TYPE_BITV;
 	return result;
diff --git a/librz/include/rz_il/rz_il_opcodes.h b/librz/include/rz_il/rz_il_opcodes.h
index bcab1e3b2d..c9b9f2790a 100644
--- a/librz/include/rz_il/rz_il_opcodes.h
+++ b/librz/include/rz_il/rz_il_opcodes.h
@@ -141,11 +141,11 @@ typedef struct rz_il_op_args_cast_t {
 
 /**
  *  \struct rz_il_op_args_append_t
- *  \brief op structure for appending 2 bitv: MSB:LSB bv1:bv2
+ *  \brief op structure for appending 2 bitv: MSB:LSB high:low
  */
 typedef struct rz_il_op_args_append_t {
-	RzILOpBitVector *x; ///< index of the bv 1
-	RzILOpBitVector *y; ///< index of the bv 2
+	RzILOpBitVector *high; ///< bitvector occupying the most significant bits
+	RzILOpBitVector *low; ///< bitvector occupying the least significant bits
 } RzILOpArgsAppend;
 
 /**
diff --git a/librz/util/bitvector.c b/librz/util/bitvector.c
index e93347b720..b0989ca90b 100644
--- a/librz/util/bitvector.c
+++ b/librz/util/bitvector.c
@@ -289,20 +289,15 @@ RZ_API RZ_OWN RzBitVector *rz_bv_cut_tail(RZ_NONNULL RzBitVector *bv, ut32 delta
 
 /**
  * Append bv2 to bv1 to get new bitvector
- * \param bv1 RzBitVector
- * \param bv2 RzBitVector
+ * \param high bitvector to occupy the most significant part of the result
+ * \param low bitvector to occupy the least significant part of the result
  * \return ret RzBitVector, the new bitvector
  */
-RZ_API RZ_OWN RzBitVector *rz_bv_append(RZ_NONNULL RzBitVector *bv1, RZ_NONNULL RzBitVector *bv2) {
-	rz_return_val_if_fail(bv1 && bv2, NULL);
-
-	ut32 new_len = bv1->len + bv2->len;
-	RzBitVector *ret = rz_bv_new(new_len);
-
-	// copy n bits from bv1
-	rz_bv_copy_nbits(bv2, 0, ret, 0, bv2->len);
-	rz_bv_copy_nbits(bv1, 0, ret, bv2->len, bv1->len);
-
+RZ_API RZ_OWN RzBitVector *rz_bv_append(RZ_NONNULL RzBitVector *high, RZ_NONNULL RzBitVector *low) {
+	rz_return_val_if_fail(high && low, NULL);
+	RzBitVector *ret = rz_bv_new(high->len + low->len);
+	rz_bv_copy_nbits(low, 0, ret, 0, low->len);
+	rz_bv_copy_nbits(high, 0, ret, low->len, high->len);
 	return ret;
 }
 
diff --git a/test/unit/test_il_vm.c b/test/unit/test_il_vm.c
index 0740ac133a..454b20d397 100644
--- a/test/unit/test_il_vm.c
+++ b/test/unit/test_il_vm.c
@@ -554,6 +554,21 @@ static bool test_rzil_vm_op_storew_be() {
 	mu_end;
 }
 
+static bool test_rzil_vm_op_append() {
+	RzILVM *vm = rz_il_vm_new(0, 8, true);
+
+	RzILOpPure *op = rz_il_op_new_append(rz_il_op_new_bitv_from_ut64(16, 0xc0ff), rz_il_op_new_bitv_from_ut64(8, 0xee));
+	RzBitVector *r = rz_il_evaluate_bitv(vm, op);
+	rz_il_op_pure_free(op);
+	mu_assert_notnull(r, "eval");
+	mu_assert_eq(rz_bv_len(r), 24, "eval len");
+	mu_assert_eq(rz_bv_to_ut64(r), 0xc0ffee, "eval val");
+	rz_bv_free(r);
+
+	rz_il_vm_free(vm);
+	mu_end;
+}
+
 bool all_tests() {
 	mu_run_test(test_rzil_vm_init);
 	mu_run_test(test_rzil_vm_basic_operation);
@@ -574,6 +589,7 @@ bool all_tests() {
 	mu_run_test(test_rzil_vm_op_storew_le);
 	mu_run_test(test_rzil_vm_op_loadw_be);
 	mu_run_test(test_rzil_vm_op_storew_be);
+	mu_run_test(test_rzil_vm_op_append);
 	return tests_passed != tests_run;
 }