diff --git a/examples/matrix.cpp b/examples/matrix.cpp
index bae0ee52b..6e6389185 100644
--- a/examples/matrix.cpp
+++ b/examples/matrix.cpp
@@ -7,6 +7,8 @@
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Support/raw_ostream.h"
 
 typedef struct yy_buffer_state * YY_BUFFER_STATE;
 extern int yyparse();
@@ -25,7 +27,7 @@ void test(fp32 *A, fp32 *B, fp32 *C, int32 i){\
     int32 u = 1;\
     u = u + i;\
     if(k == 0)\
-     u = u + 2;\
+     j = u + 2;\
   }\
 }\
 ";
@@ -41,8 +43,8 @@ int main() {
    llvm::LLVMContext llvm_context;
    llvm::Module llvm_module("test", llvm_context);
    tdl::codegen::lowering(module, llvm_module);
-//   llvm::PrintModulePass print(llvm::outs());
-//   llvm::AnalysisManager<llvm::Module> analysis;
-//   print.run(*module.handle(), analysis);
+   llvm::PrintModulePass print(llvm::outs());
+   llvm::AnalysisManager<llvm::Module> analysis;
+   print.run(llvm_module, analysis);
    return 0;
 }
diff --git a/include/ast/ast.h b/include/ast/ast.h
index 031d49f74..d9b24f8e4 100644
--- a/include/ast/ast.h
+++ b/include/ast/ast.h
@@ -264,6 +264,17 @@ public:
 class statement: public node{
 };
 
+class expression_statement: public statement{
+public:
+  expression_statement(node *expr)
+    : expr_((expression*)expr){ }
+
+  ir::value* codegen(ir::module * mod) const;
+
+private:
+  expression *expr_;
+};
+
 class compound_statement: public statement{
   typedef list<declaration*>* declarations_t;
   typedef list<statement*>* statements_t;
diff --git a/include/ast/parser.y b/include/ast/parser.y
index bcfd7498d..2806f49ea 100644
--- a/include/ast/parser.y
+++ b/include/ast/parser.y
@@ -278,7 +278,7 @@ statement_list
 	
 expression_statement
 	: ';' { $$ = new no_op(); }
-	| expression ';' { $$ = $1; }
+  | expression ';' { $$ = new expression_statement($1); }
 	;
 
 selection_statement
diff --git a/include/codegen/lowering.h b/include/codegen/lowering.h
index 673bcbf09..a660e5706 100644
--- a/include/codegen/lowering.h
+++ b/include/codegen/lowering.h
@@ -91,8 +91,8 @@ Instruction *llvm_inst(ir::instruction *inst, LLVMContext & ctx,
     return PHINode::Create(ty, num_ops, ii->get_name());
   }
   if(auto* ii = dynamic_cast<ir::return_inst*>(inst)){
-    Value *ret_val = value(ii->get_return_value());
-    return ReturnInst::Create(ctx, ret_val);
+    ir::value *ret_val = ii->get_return_value();
+    return ReturnInst::Create(ctx, ret_val?value(ret_val):nullptr);
   }
   if(auto* ii = dynamic_cast<ir::binary_operator*>(inst)){
     Value *lhs = value(ii->get_operand(0));
@@ -139,9 +139,9 @@ Value* llvm_value(ir::value *v, LLVMContext &ctx,
     return vmap.at(v);
   // create operands
   if(auto *uu = dynamic_cast<ir::user*>(v))
-  for(ir::use u: uu->ops())
+  for(ir::use u: uu->ops()){
     vmap[u.get()] = llvm_value(u, ctx, vmap, bmap);
-  // constant
+  }
   if(auto *cc = dynamic_cast<ir::constant*>(v))
     return llvm_constant(cc, ctx);
   // instruction
@@ -159,12 +159,12 @@ void lowering(ir::module &src, Module &dst){
   // iterate over functions
   for(ir::function *fn: src.get_function_list()) {
     // create LLVM function
-    Type *fn_ty = llvm_type(fn->get_type(), dst_ctx);
-    Function *dst_fn = (Function*)dst.getOrInsertFunction(fn->get_name(), fn_ty);
+    FunctionType *fn_ty = (FunctionType*)llvm_type(fn->get_fn_type(), dst_ctx);
+    Function *dst_fn = Function::Create(fn_ty, Function::ExternalLinkage, "kernel", &dst);
+//    std::cout << ((FunctionType*)fn_ty)->getNumParams() << std::endl;
     // map parameters
-    for(unsigned i = 0; i < fn->args().size(); i++) {
+    for(unsigned i = 0; i < fn->args().size(); i++)
       vmap[fn->args()[i]] = &*(dst_fn->arg_begin() + i);
-    }
     // create blocks
     for(ir::basic_block *block: fn->blocks()) {
       BasicBlock *dst_block = BasicBlock::Create(dst_ctx, block->get_name(), dst_fn);
@@ -176,6 +176,7 @@ void lowering(ir::module &src, Module &dst){
       for(ir::instruction *inst: block->get_inst_list()) {
         Instruction *dst_inst = llvm_inst(inst, dst_ctx, vmap, bmap);
         vmap[inst] = dst_inst;
+        dst_builder.Insert(dst_inst);
       }
     }
     // add phi operands
diff --git a/include/ir/function.h b/include/ir/function.h
index 4becaa606..4f0762067 100644
--- a/include/ir/function.h
+++ b/include/ir/function.h
@@ -46,9 +46,10 @@ private:
            const std::string &name = "", module *parent = nullptr);
 
 public:
-  // arguments
+  // accessors
   const args_t &args() { return args_; }
-  // Factory methods
+  function_type* get_fn_type() { return fn_ty_; }
+  // factory methods
   static function *create(function_type *ty, linkage_types_t linkage,
                           const std::string &name, module *mod);
   // blocks
diff --git a/lib/ast/lowering.cpp b/lib/ast/lowering.cpp
index 9dba1e633..7d9d79235 100644
--- a/lib/ast/lowering.cpp
+++ b/lib/ast/lowering.cpp
@@ -117,6 +117,11 @@ ir::value* compound_statement::codegen(ir::module* mod) const{
   return nullptr;
 }
 
+/* expression statement */
+ir::value* expression_statement::codegen(ir::module *mod) const{
+  return expr_->codegen(mod);
+}
+
 /* Iteration statement */
 ir::value* iteration_statement::codegen(ir::module *mod) const{
   ir::builder &builder = mod->get_builder();
diff --git a/lib/ir/instructions.cpp b/lib/ir/instructions.cpp
index 03f85bec6..3dd2ccd44 100644
--- a/lib/ir/instructions.cpp
+++ b/lib/ir/instructions.cpp
@@ -191,7 +191,7 @@ cast_inst *cast_inst::create_integer_cast(value *arg, type *ty, bool is_signed,
 
 // return_inst
 return_inst::return_inst(context &ctx, value *ret_val, instruction *next)
-    : terminator_inst(type::get_void_ty(ctx), !!ret_val, "", next){
+    : terminator_inst(type::get_void_ty(ctx), ret_val!=nullptr, "", next){
   if(ret_val)
     set_operand(0, ret_val);
 }