diff --git a/src/mapleall/maple_be/src/be/lower.cpp b/src/mapleall/maple_be/src/be/lower.cpp
index d3e70932fb66a8921c829031880e71db69793aa8..bbde064389a2fcc8903a0f120f430bf1db21a4b8 100644
--- a/src/mapleall/maple_be/src/be/lower.cpp
+++ b/src/mapleall/maple_be/src/be/lower.cpp
@@ -2667,7 +2667,7 @@ BaseNode *CGLowerer::LowerExpr(BaseNode &parent, BaseNode &expr, BlockNode &blkN
   bool isCvtU1Expr = (expr.GetOpCode() == OP_cvt && expr.GetPrimType() == PTY_u1 &&
       static_cast<TypeCvtNode&>(expr).FromType() != PTY_u1);
   if (expr.GetPrimType() == PTY_u1) {
-    expr.SetPrimType(PTY_u8);
+    expr.SetPrimType(PTY_i32);
   }
   if (expr.GetOpCode() == OP_intrinsicopwithtype) {
     return LowerIntrinsicopwithtype(parent, static_cast<IntrinsicopNode&>(expr), blkNode);
diff --git a/src/mapleall/maple_me/include/lmbc_lower.h b/src/mapleall/maple_me/include/lmbc_lower.h
index 385ac8cd4e033af0dd5b4c8852762b5bb8f5bbbf..0641d0b4ccc8985d96680f0933c7712839ac165a 100644
--- a/src/mapleall/maple_me/include/lmbc_lower.h
+++ b/src/mapleall/maple_me/include/lmbc_lower.h
@@ -42,6 +42,7 @@ class LMBCLowerer {
   void LowerReturn(NaryStmtNode *retNode, BlockNode *newblk);
   void LowerCall(NaryStmtNode *stmt, BlockNode *newblk);
   BlockNode *LowerBlock(BlockNode *);
+  void FixPrototype4FirstArgReturn(IcallNode *icall);
   void LowerFunction();
 
   MIRModule *mirModule;
diff --git a/src/mapleall/maple_me/src/lmbc_lower.cpp b/src/mapleall/maple_me/src/lmbc_lower.cpp
index bab9b20c21f6afd72408f4d654012852af945c01..39c4a9d1c2b7cd2857213503ee9af4b3788278c5 100644
--- a/src/mapleall/maple_me/src/lmbc_lower.cpp
+++ b/src/mapleall/maple_me/src/lmbc_lower.cpp
@@ -230,9 +230,13 @@ void LMBCLowerer::LowerDassign(DassignNode *dsnode, BlockNode *newblk) {
   }
   BaseNode *rhs = LowerExpr(dsnode->Opnd(0));
   if (rhs->GetPrimType() != PTY_agg || rhs->GetOpCode() == OP_regread) {
+    PrimType ptypUsed = symty->GetPrimType();
+    if (ptypUsed == PTY_agg) {
+      ptypUsed = rhs->GetPrimType();
+    }
     if (!symbol->LMBCAllocateOffSpecialReg()) {
       BaseNode *base = mirBuilder->CreateExprDreadoff(OP_addrofoff, LOWERED_PTR_TYPE, *symbol, 0);
-      IassignoffNode *iassignoff = mirBuilder->CreateStmtIassignoff(symty->GetPrimType(),
+      IassignoffNode *iassignoff = mirBuilder->CreateStmtIassignoff(ptypUsed,
                                                                     offset, base, rhs);
       newblk->AddStatement(iassignoff);
       return;
@@ -240,7 +244,7 @@ void LMBCLowerer::LowerDassign(DassignNode *dsnode, BlockNode *newblk) {
     PregIdx spcreg = GetSpecialRegFromSt(symbol);
     if (spcreg == -kSregFp) {
       IassignFPoffNode *iassignoff = mirBuilder->CreateStmtIassignFPoff(OP_iassignfpoff,
-          symty->GetPrimType(),
+          ptypUsed,
           memlayout->sym_alloc_table[symbol->GetStIndex()].offset + offset, rhs);
       newblk->AddStatement(iassignoff);
     } else {
@@ -248,7 +252,7 @@ void LMBCLowerer::LowerDassign(DassignNode *dsnode, BlockNode *newblk) {
       SymbolAlloc &symalloc = symbol->IsLocal() ?
           memlayout->sym_alloc_table[symbol->GetStIndex()] :
           globmemlayout->sym_alloc_table[symbol->GetStIndex()];
-      IassignoffNode *iassignoff = mirBuilder->CreateStmtIassignoff(symty->GetPrimType(),
+      IassignoffNode *iassignoff = mirBuilder->CreateStmtIassignoff(ptypUsed,
                                                                     symalloc.offset + offset,
                                                                     rrn,
                                                                     rhs);
@@ -424,6 +428,31 @@ void LMBCLowerer::LowerCall(NaryStmtNode *stmt, BlockNode *newblk) {
   newblk->AddStatement(stmt);
 }
 
+void LMBCLowerer::FixPrototype4FirstArgReturn(IcallNode *icall) {
+  MIRFuncType *ftype = static_cast<MIRFuncType*>(GlobalTables::GetTypeTable().GetTypeFromTyIdx(icall->GetRetTyIdx()));
+  if (!ftype->FirstArgReturn()) {
+    return;
+  }
+  MIRType *retType = GlobalTables::GetTypeTable().GetTypeFromTyIdx(ftype->GetRetTyIdx());
+  if (retType->GetPrimType() == PTY_void) {
+    return;
+  }
+  // insert return type as fake first parameter
+  size_t oldSize = ftype->GetParamTypeList().size();
+  ftype->GetParamTypeList().push_back(TyIdx(0));
+  ftype->GetParamAttrsList().push_back(TypeAttrs());
+  for (size_t i = oldSize; i > 0; i--) {
+    ftype->GetParamTypeList()[i] = ftype->GetParamTypeList()[i-1];
+    ftype->GetParamAttrsList()[i] = ftype->GetParamAttrsList()[i-1];
+  }
+  MIRType *newType = GlobalTables::GetTypeTable().GetOrCreatePointerType(ftype->GetRetTyIdx(), GetExactPtrPrimType(), ftype->GetRetAttrs());
+  ftype->GetParamTypeList()[0] = newType->GetTypeIndex();
+  ftype->GetParamAttrsList()[0] = TypeAttrs();
+  // change return type to void
+  ftype->SetRetTyIdx(GlobalTables::GetTypeTable().GetVoid()->GetTypeIndex());
+  ftype->SetRetAttrs(TypeAttrs());
+}
+
 BlockNode *LMBCLowerer::LowerBlock(BlockNode *block) {
   BlockNode *newblk = mirModule->CurFuncCodeMemPool()->New<BlockNode>();
   if (!block->GetFirst()) {
@@ -460,9 +489,11 @@ BlockNode *LMBCLowerer::LowerBlock(BlockNode *block) {
         }
         break;
       }
+      case OP_icallproto:
+        FixPrototype4FirstArgReturn(static_cast<IcallNode *>(stmt));
+        // fall thru
       case OP_asm:
-      case OP_call:
-      case OP_icallproto: {
+      case OP_call: {
         LowerCall(static_cast<NaryStmtNode*>(stmt), newblk);
         break;
       }