diff --git a/pyecoreocl/compiler.py b/pyecoreocl/compiler.py
index 682061d..3c7b933 100644
--- a/pyecoreocl/compiler.py
+++ b/pyecoreocl/compiler.py
@@ -76,9 +76,11 @@ def visitBooleanBinaryOperation(self, ctx):
             self.visit(ctx.right)
             self.inline(")")
             return
+        self.inline("(")
         self.visit(ctx.left)
         self.inline(f" {operator} ")
         self.visit(ctx.right)
+        self.inline(")")
 
     def visitCallExpression(self, ctx):
         self.visit(ctx.expression)
diff --git a/tests/test_expressions_strict.py b/tests/test_expressions_strict.py
index 88cf008..3b772ba 100644
--- a/tests/test_expressions_strict.py
+++ b/tests/test_expressions_strict.py
@@ -45,11 +45,11 @@ def test__booleans():
     assert !true! is True
     assert !false! is False
 
-    assert (!not true!) is False
-    assert (!not false!) is True
+    assert !not true! is False
+    assert !not false! is True
 
     assert !(true or true)! is True
-    assert !(true or false)! is True
+    assert !true or false! is True
     assert !(false or true)! is True
     assert !(false or false)! is False