diff --git a/nolang/lexer.py b/nolang/lexer.py
index d6cb4ae..5378560 100644
--- a/nolang/lexer.py
+++ b/nolang/lexer.py
@@ -4,8 +4,10 @@ from rply import LexerGenerator
 RULES = [
     ('INTEGER', r'\d+'),
     ('PLUS', r'\+'),
+    ('MINUS', r'\-'),
     ('LT', r'\<'),
-    ('EQUALS', r'='),
+    ('EQ', r'=='),
+    ('ASSIGN', r'='),
     ('FUNCTION', r'function'),
     ('RETURN', r'return'),
     ('VAR', r'var'),
diff --git a/nolang/parser.py b/nolang/parser.py
index ac2f8f3..d075e6f 100644
--- a/nolang/parser.py
+++ b/nolang/parser.py
@@ -80,8 +80,8 @@ def get_parser():
     def var_decl_identifier(state, p):
         return ast.VarDeclPartial([p[1].getstr()] + p[2].get_names())
 
-    @pg.production('statement : IDENTIFIER EQUALS expression SEMICOLON')
-    def statement_identifier_equals_expr(state, p):
+    @pg.production('statement : IDENTIFIER ASSIGN expression SEMICOLON')
+    def statement_identifier_assign_expr(state, p):
         return ast.Assignment(p[0].getstr(), p[2])
 
     @pg.production('statement : RETURN expression SEMICOLON')
@@ -140,12 +140,14 @@ def get_parser():
         return p[1]
 
     @pg.production('expression : expression PLUS expression')
+    @pg.production('expression : expression MINUS expression')
     def expression_plus_expression(state, p):
-        return ast.BinOp('+', p[0], p[2])
+        return ast.BinOp(p[1].getstr(), p[0], p[2])
 
     @pg.production('expression : expression LT expression')
+    @pg.production('expression : expression EQ expression')
     def expression_lt_expression(state, p):
-        return ast.BinOp('<', p[0], p[2])
+        return ast.BinOp(p[1].getstr(), p[0], p[2])
 
     @pg.production('expression_list : ')
     def expression_list_empty(state, p):
diff --git a/tests/test_interpreter.py b/tests/test_interpreter.py
index aeb81b7..162589b 100644
--- a/tests/test_interpreter.py
+++ b/tests/test_interpreter.py
@@ -123,8 +123,16 @@ class TestInterpreter(BaseTest):
             ''')
         assert self.space.int_w(w_res) == 4
 
-    # def test_recursive_call(self):
-    #     w_res = self.interpret('''
-    #         function fib(n) {
-    #             if n == 0 or n == 1
-    #         }
\ No newline at end of file
+    def test_recursive_call(self):
+        w_res = self.interpret('''
+            function fib(n) {
+                if n == 0 or n == 1 {
+                    return 1;
+                }
+                return fib(n - 1) + fib(n - 2);
+            }
+            function main() {
+                return fib(5);
+            }
+            ''')
+        assert self.space.int_w(w_res) == 8