diff --git a/sayaka/Makefile b/sayaka/Makefile
index e8fa15a..aec276c 100644
--- a/sayaka/Makefile
+++ b/sayaka/Makefile
@@ -1,8 +1,8 @@
 CC = g++
 CFLAGS = -c -g -std=c++11 -fexceptions
 LDFLAGS = -g -rdynamic
-LLVM_COMPILER_FLAGS = $(shell llvm-config --libs core jit native --cxxflags)
-LLVM_LINKER_FLAGS = $(shell llvm-config --libs core jit native --ldflags)
+LLVM_COMPILER_FLAGS = $(shell llvm-config --cxxflags)
+LLVM_LINKER_FLAGS = $(shell llvm-config --ldflags --libs core jit native)
 EXECUTABLE = sayaka
 SRC_DIR = src
 BIN_DIR = bin
@@ -13,14 +13,11 @@ OBJS = $(subst $(SRC_DIR),$(BIN_DIR),$(subst .cpp,.o,$(SOURCES)))
 
 all: $(BIN_DIR) $(PARSER_SOURCE) $(LEXER_SOURCE) $(BIN_DIR)/$(EXECUTABLE)
 
-debug: all
-	gdb $(BIN_DIR)/$(EXECUTABLE)
-
-valgrind: all
-	valgrind --leak-check=yes $(BIN_DIR)/$(EXECUTABLE)
-
 $(BIN_DIR)/$(EXECUTABLE): $(OBJS)
-	$(CC) $(OBJS) -o $(BIN_DIR)/$(EXECUTABLE) $(LLVM_LINKER_FLAGS) $(LDFLAGS)
+	$(CC) $(OBJS) -o $@ $(LLVM_LINKER_FLAGS) $(LDFLAGS)
+
+$(BIN_DIR)/%.o: $(SRC_DIR)/%.cpp
+	$(CC) $(LLVM_COMPILER_FLAGS) $(CFLAGS) $< -o $@
 
 $(LEXER_SOURCE): $(SRC_DIR)/lexer.l
 	flex --outfile=$@ --header-file=$(SRC_DIR)/lexer.h $(SRC_DIR)/lexer.l
@@ -28,8 +25,11 @@ $(LEXER_SOURCE): $(SRC_DIR)/lexer.l
 $(PARSER_SOURCE): $(SRC_DIR)/parser.y
 	bison --defines=$(SRC_DIR)/parser.h --output=$@ --verbose --report-file=$(BIN_DIR)/parser.log $(SRC_DIR)/parser.y
 
-$(BIN_DIR)/%.o: $(SRC_DIR)/%.cpp
-	$(CC) $(LLVM_COMPILER_FLAGS) $(CFLAGS) $< -o $@
+debug: all
+	gdb $(BIN_DIR)/$(EXECUTABLE)
+
+valgrind: all
+	valgrind --leak-check=yes $(BIN_DIR)/$(EXECUTABLE)
 
 $(BIN_DIR):
 	mkdir -p $(BIN_DIR)
@@ -39,4 +39,4 @@ clean:
 	rm -f $(LEXER_SOURCE) $(SRC_DIR)/lexer.h $(PARSER_SOURCE) $(SRC_DIR)/parser.h
 
 playground: $(BIN_DIR)
-	$(CC) $(SRC_DIR)/playground.cpp -o $(BIN_DIR)/playground.o
+	$(CC) $(SRC_DIR)/playground.cpp -o $(BIN_DIR)/playground.o $(shell llvm-config --libs core jit native --cxxflags --ldflags)
diff --git a/sayaka/src/ast_node.h b/sayaka/src/ast_node.h
index 9816dfd..6973673 100644
--- a/sayaka/src/ast_node.h
+++ b/sayaka/src/ast_node.h
@@ -2,37 +2,12 @@
 #define __AST_NODE_H_
 
 #include <iostream>
+#include <vector>
+#include <tuple>
 #include <llvm/IR/Value.h>
 #include "ast_type.h"
 #include "code_gen_context.h"
 
-union tagUNumberValue {
-	int8_t b;
-	uint8_t ub;
-	int16_t s;
-	uint16_t us;
-	int32_t i;
-	uint32_t ui;
-	int64_t l;
-	uint64_t ul;
-	float f;
-	double d;
-};
-
-
-enum tagENumberType {
-	eBYTE = 0,
-	eUBYTE = 1,
-	eSHORT = (1 << 1),
-	eUSHORT = (1 << 1) | 1,
-	eINT = (1 << 2),
-	eUINT = (1 << 2) | 1,
-	eLONG = (1 << 3),
-	eULONG = (1 << 3) | 1,
-	eFLOAT = (1 << 4),
-	eDOUBLE = (1 << 5),
-};
-
 enum tagEBinaryOperationType {
 	eMULTIPLY,
 	eADD,
@@ -41,8 +16,6 @@ enum tagEBinaryOperationType {
 	ePOW,
 };
 
-typedef union tagUNumberValue UNumberValue;
-typedef enum tagENumberType ENumberType;
 typedef enum tagEBinaryOperationType EBinaryOperationType;
 
 class ASTNode {
@@ -67,7 +40,6 @@ class ASTNodeIdentifier : public ASTNode {
 
 class ASTNodePrimitive : public ASTNode {
 public:
-	UNumberValue val;
 	std::string str;
 
 	ASTNodePrimitive(std::string);
@@ -150,4 +122,29 @@ class ASTNodeFunction : public ASTNode {
 	virtual ASTNodeFunction* pass_types(CodeGenContext*, ASTType*) override;
 };
 
+class ASTNodeFunctionPrototype : public ASTNode {
+public:
+	std::string return_type;
+	std::string function_name;
+	std::vector<std::tuple<std::string, std::string>>* args;
+
+	ASTNodeFunctionPrototype(std::string, std::string, std::vector<std::tuple<std::string, std::string>>*);
+
+	virtual ~ASTNodeFunctionPrototype();
+	virtual llvm::Value* gen_code(CodeGenContext*) override;
+	virtual ASTNodeFunctionPrototype* pass_types(CodeGenContext*, ASTType*) override;
+};
+
+class ASTNodeFunctionCall : public ASTNode {
+public:
+	std::string function_name;
+	std::vector<ASTNode*>* args;
+
+	ASTNodeFunctionCall(std::string, std::vector<ASTNode*>*);
+
+	virtual ~ASTNodeFunctionCall();
+	virtual llvm::Value* gen_code(CodeGenContext*) override;
+	virtual ASTNodeFunctionCall* pass_types(CodeGenContext*, ASTType*) override;
+};
+
 #endif /* __AST_NODE_H_ */
diff --git a/sayaka/src/ast_node_functioncall.cpp b/sayaka/src/ast_node_functioncall.cpp
new file mode 100644
index 0000000..ff6f06e
--- /dev/null
+++ b/sayaka/src/ast_node_functioncall.cpp
@@ -0,0 +1,33 @@
+#include "ast_node.h"
+
+ASTNodeFunctionCall::ASTNodeFunctionCall(std::string function_name, std::vector<ASTNode*>* args) {
+	this->function_name = function_name;
+	this->args = args;
+}
+
+ASTNodeFunctionCall::~ASTNodeFunctionCall() {
+	for (std::vector<ASTNode*>::iterator it = this->args->begin(); it != this->args->end(); it++) {
+		delete *it;
+	}
+	delete this->args;
+}
+
+ASTNodeFunctionCall* ASTNodeFunctionCall::pass_types(CodeGenContext* code_gen_context, ASTType* type) {
+	this->type = code_gen_context->ast_types_resolver.double_ty();
+	for (std::vector<ASTNode*>::iterator it = this->args->begin(); it != this->args->end(); it++) {
+		*it = (*it)->pass_types(code_gen_context, type);
+	}
+	return this;
+}
+
+llvm::Value* ASTNodeFunctionCall::gen_code(CodeGenContext* code_gen_context) {
+	llvm::Function* callee = code_gen_context->module->getFunction(this->function_name);
+	if (callee == NULL) {
+		throw std::runtime_error("Unknown function called");
+	}
+	std::vector<llvm::Value*> argsv;
+	for (std::vector<ASTNode*>::iterator it = this->args->begin(); it != this->args->end(); it++) {
+		argsv.push_back((*it)->gen_code(code_gen_context));
+	}
+	return code_gen_context->builder.CreateCall(callee, argsv, "calltmp");
+}
diff --git a/sayaka/src/ast_node_functionprototype.cpp b/sayaka/src/ast_node_functionprototype.cpp
new file mode 100644
index 0000000..5554152
--- /dev/null
+++ b/sayaka/src/ast_node_functionprototype.cpp
@@ -0,0 +1,27 @@
+#include "ast_node.h"
+
+ASTNodeFunctionPrototype::ASTNodeFunctionPrototype(std::string return_type, std::string function_name, std::vector<std::tuple<std::string, std::string>>* args) {
+	this->return_type = return_type;
+	this->function_name = function_name;
+	this->args = args;
+}
+
+ASTNodeFunctionPrototype::~ASTNodeFunctionPrototype() {
+	delete this->args;
+}
+
+ASTNodeFunctionPrototype* ASTNodeFunctionPrototype::pass_types(CodeGenContext* code_gen_context, ASTType* type) {
+	this->type = code_gen_context->ast_types_resolver.int_ty();
+	return this;
+}
+
+llvm::Value* ASTNodeFunctionPrototype::gen_code(CodeGenContext* code_gen_context) {
+	std::vector<llvm::Type*> args_types_list;
+	for (std::vector<std::tuple<std::string, std::string>>::iterator it = this->args->begin(); it != this->args->end(); it++) {
+		args_types_list.push_back(code_gen_context->ast_types_resolver.get(std::get<0>(*it))->llvm_type);
+	}
+	llvm::FunctionType* ft = llvm::FunctionType::get(code_gen_context->ast_types_resolver.get(this->return_type)->llvm_type, args_types_list, false);
+	llvm::Function* fn = llvm::Function::Create(ft, llvm::Function::ExternalLinkage, this->function_name, code_gen_context->module);
+	return llvm::ConstantInt::get(code_gen_context->ast_types_resolver.int_ty()->llvm_type, 0, true);
+}
+
diff --git a/sayaka/src/lexer.l b/sayaka/src/lexer.l
index cdb1648..465d16c 100644
--- a/sayaka/src/lexer.l
+++ b/sayaka/src/lexer.l
@@ -29,6 +29,7 @@ SUBTRACT "-"
 DIVIDE "/"
 POW "*\\*"
 EQUALS "="
+COMMA ","
 
 IDENTIFIER [a-z_][a-zA-Z0-9_]*
 TYPE_NAME [A-Z][a-zA-Z0-9_]*
@@ -53,6 +54,7 @@ WS [ \r\n\t]+
 {RBRACKET} { return TOKEN_RBRACKET; }
 {SEMICOLON} { return TOKEN_SEMICOLON; }
 {EQUALS} { return TOKEN_EQUALS; }
+{COMMA} { return TOKEN_COMMA; }
 
 {NUMBER} { SAVE_TOKEN; return TOKEN_NUMBER; }
 {IDENTIFIER} { SAVE_TOKEN; return TOKEN_IDENTIFIER; }
diff --git a/sayaka/src/main.cpp b/sayaka/src/main.cpp
index 800c5c6..1d7434a 100644
--- a/sayaka/src/main.cpp
+++ b/sayaka/src/main.cpp
@@ -11,6 +11,12 @@ namespace boost {
 }
 #endif // BOOST_NO_EXCEPTIONS
 
+extern "C" {
+	int32_t test_fn(int32_t x) {
+		return x * 2;
+	}
+}
+
 int main(int argc, char* argv[]) {
 	Compiler compiler;
 	compiler.llvm_initialize();
diff --git a/sayaka/src/parser.y b/sayaka/src/parser.y
index a191271..6d85a19 100644
--- a/sayaka/src/parser.y
+++ b/sayaka/src/parser.y
@@ -15,6 +15,9 @@ void yyerror(YYLTYPE* llocp, ASTNode**, yyscan_t scanner, const char *s) {
 
 %code requires {
 
+#include <vector>
+#include <tuple>
+
 class ASTNode;
 class ASTNodeBlock;
 class ASTNodeIdentifier;
@@ -38,6 +41,8 @@ typedef void* yyscan_t;
 	ASTNode* node;
 	ASTNodeBlock* block;
 	ASTNodeIdentifier* identifier;
+	std::vector<std::tuple<std::string, std::string>>* typed_args_list;
+	std::vector<ASTNode*>* args_list;
 	std::string* str;
 }
 
@@ -48,11 +53,14 @@ typedef void* yyscan_t;
 
 %token TOKEN_LPAREN TOKEN_RPAREN TOKEN_SEMICOLON TOKEN_EQUALS TOKEN_LBRACE TOKEN_RBRACE TOKEN_LBRACKET TOKEN_RBRACKET
 %token TOKEN_ADD TOKEN_MULTIPLY TOKEN_DIVIDE TOKEN_SUBTRACT TOKEN_POW
+%token TOKEN_COMMA
 %token <str> TOKEN_NUMBER TOKEN_IDENTIFIER TOKEN_TYPE_NAME
 
-%type <node> program expr number binary_operator_expr assignment_expr variable_declaration_expr cast_expr
+%type <node> program expr number binary_operator_expr assignment_expr variable_declaration_expr cast_expr function_call_expr function_prototype_expr
 %type <block> stmts
 %type <identifier> identifier
+%type <typed_args_list> typed_args_list
+%type <args_list> args_list
 
 %start program
 
@@ -77,6 +85,8 @@ expr
 	| variable_declaration_expr { $$ = $1; }
 	| assignment_expr { $$ = $1; }
 	| cast_expr { $$ = $1; }
+	| function_prototype_expr { $$ = $1; }
+	| function_call_expr { $$ = $1; }
 	| binary_operator_expr { $$ = $1; }
 	;
 
@@ -120,3 +130,43 @@ binary_operator_expr
 	| expr TOKEN_MULTIPLY expr { $$ = new ASTNodeBinaryOperator(eMULTIPLY, $1, $3); }
 	| expr TOKEN_POW expr { $$ = new ASTNodeBinaryOperator(ePOW, $1, $3); }
 	;
+
+function_prototype_expr
+	: TOKEN_TYPE_NAME TOKEN_IDENTIFIER TOKEN_LPAREN typed_args_list TOKEN_RPAREN {
+		$$ = new ASTNodeFunctionPrototype(*$1, *$2, $4);
+		delete $1;
+		delete $2;
+	}
+	;
+
+
+typed_args_list
+	: TOKEN_TYPE_NAME TOKEN_IDENTIFIER {
+		$$ = new std::vector<std::tuple<std::string, std::string>>();
+		$$->push_back(std::make_tuple(*$1, *$2));
+		delete $1;
+		delete $2;
+	}
+	| typed_args_list TOKEN_COMMA TOKEN_TYPE_NAME TOKEN_IDENTIFIER {
+		$$->push_back(std::make_tuple(*$3, *$4));
+		delete $3;
+		delete $4;
+	}
+	;
+
+args_list
+	: expr {
+		$$ = new std::vector<ASTNode*>();
+		$$->push_back($1);
+	}
+	| args_list TOKEN_COMMA expr {
+		$$->push_back($3);
+	}
+	;
+
+function_call_expr
+	: TOKEN_IDENTIFIER TOKEN_LPAREN args_list TOKEN_RPAREN {
+		$$ = new ASTNodeFunctionCall(*$1, $3);
+		delete $1;
+	}
+	;
diff --git a/sayaka/src/playground.cpp b/sayaka/src/playground.cpp
index aee052c..6add888 100644
--- a/sayaka/src/playground.cpp
+++ b/sayaka/src/playground.cpp
@@ -2,6 +2,8 @@
 #include <iostream>
 #include <map>
 #include <sstream>
+#include <llvm/Support/TargetSelect.h>
+#include <llvm/Support/ManagedStatic.h>
 
 void test_map_nonexisting_key() {
 	std::cout << "Testing map non-existing key" << std::endl;
@@ -57,11 +59,17 @@ void test_virtual_destructors() {
 	std::cout << "---" << std::endl;
 }
 
+void test_llvm_memory() {
+	llvm::InitializeNativeTarget();
+	llvm::llvm_shutdown();
+}
+
 int main() {
 	test_map_nonexisting_key();
 	test_pointer_size();
 	test_string_concat();
 	test_string_stream();
 	test_virtual_destructors();
+	test_llvm_memory();
 	return 0;
 }