diff --git a/src/jsonata/jsonata.py b/src/jsonata/jsonata.py
index 0a8392b..55476e0 100644
--- a/src/jsonata/jsonata.py
+++ b/src/jsonata/jsonata.py
@@ -800,9 +800,9 @@ def evaluate_equality_expression(self, lhs: Optional[Any], rhs: Optional[Any], o
 
         result = None
         if op == "=":
-            result = lhs == rhs  # isDeepEqual(lhs, rhs);
+            result = utils.Utils.is_deep_equal(lhs, rhs)
         elif op == "!=":
-            result = lhs != rhs  # !isDeepEqual(lhs, rhs);
+            result = not utils.Utils.is_deep_equal(lhs, rhs)
         return result
 
     #
diff --git a/src/jsonata/utils.py b/src/jsonata/utils.py
index 242e134..8b43aea 100644
--- a/src/jsonata/utils.py
+++ b/src/jsonata/utils.py
@@ -90,6 +90,27 @@ def create_sequence_from_iter(it: Iterable) -> list:
         sequence.sequence = True
         return sequence
 
+    @staticmethod
+    def is_deep_equal(lhs: Optional[Any], rhs: Optional[Any]) -> bool:
+        if isinstance(lhs, list) and isinstance(rhs, list):
+            if len(lhs) != len(rhs):
+                return False
+            for ii, _ in enumerate(lhs):
+                if not Utils.is_deep_equal(lhs[ii], rhs[ii]):
+                    return False
+            return True
+        elif isinstance(lhs, dict) and isinstance(rhs, dict):
+            if lhs.keys() != rhs.keys():
+                return False
+            for key in lhs.keys():
+                if not Utils.is_deep_equal(lhs[key], rhs[key]):
+                    return False
+            return True
+        if lhs == rhs and type(lhs) == type(rhs):
+            return True
+
+        return False
+
     class JList(list):
         sequence: bool
         outer_wrapper: bool
diff --git a/tests/types_test.py b/tests/types_test.py
index 26afcad..0b8b076 100644
--- a/tests/types_test.py
+++ b/tests/types_test.py
@@ -40,3 +40,10 @@ def test_ignore(self):
         expr2.set_validate_input(False)
         with pytest.raises(TypeError):
             expr2.evaluate({"a": a_set})
+
+    def test_fix_issue_21(self):
+        """
+        https://github.com/rayokota/jsonata-python/issues/21
+        """
+        assert jsonata.Jsonata("true = 1").evaluate({}) is False
+        assert jsonata.Jsonata("false = 0").evaluate({}) is False