diff --git a/Orange/widgets/data/owfeatureconstructor.py b/Orange/widgets/data/owfeatureconstructor.py
index 5c22b338767..57eb0c784d7 100644
--- a/Orange/widgets/data/owfeatureconstructor.py
+++ b/Orange/widgets/data/owfeatureconstructor.py
@@ -11,7 +11,6 @@
 import builtins
 import math
 import random
-import logging
 import ast
 import types
 import unicodedata
@@ -448,8 +447,6 @@ def freevars(exp: ast.AST, env: List[str]):
     elif etype == ast.Starred:
         # a 'starred' call parameter (e.g. a and b in `f(x, *a, *b)`
         return freevars(exp.value, env)
-    elif etype in [ast.Num, ast.Str, ast.Ellipsis, ast.Bytes, ast.NameConstant]:
-        return []
     elif etype == ast.Constant:
         return []
     elif etype == ast.Attribute:
@@ -466,10 +463,6 @@ def freevars(exp: ast.AST, env: List[str]):
         return sum((freevars(e, env)
                     for e in filter(None, [exp.lower, exp.upper, exp.step])),
                    [])
-    elif etype == ast.ExtSlice:
-        return sum((freevars(e, env) for e in exp.dims), [])
-    elif etype == ast.Index:
-        return freevars(exp.value, env)
     elif etype == ast.keyword:
         return freevars(exp.value, env)
     else:
@@ -997,8 +990,6 @@ def validate_exp(exp):
         return all(map(validate_exp, subexp))
     elif etype == ast.Starred:
         return validate_exp(exp.value)
-    elif etype in [ast.Num, ast.Str, ast.Bytes, ast.Ellipsis, ast.NameConstant]:
-        return True
     elif etype == ast.Constant:
         return True
     elif etype == ast.Attribute:
diff --git a/Orange/widgets/data/tests/test_owfeatureconstructor.py b/Orange/widgets/data/tests/test_owfeatureconstructor.py
index ecca91de297..9c838803631 100644
--- a/Orange/widgets/data/tests/test_owfeatureconstructor.py
+++ b/Orange/widgets/data/tests/test_owfeatureconstructor.py
@@ -203,13 +203,15 @@ def freevars_(source, env=None):
         self.assertEqual(freevars_("a + b", ["a", "b"]), [])
         self.assertEqual(freevars_("a[b]"), ["a", "b"])
         self.assertEqual(freevars_("a[b]", ["a", "b"]), [])
+        self.assertEqual(freevars_("a[b:3]", ["a", "b"]), [])
+        self.assertEqual(freevars_("a[b:c:d]", ["a", "b", "c", "d"]), [])
+
         self.assertEqual(freevars_("f(x, *a)", ["f"]), ["x", "a"])
         self.assertEqual(freevars_("f(x, *a, y=1)", ["f"]), ["x", "a"])
         self.assertEqual(freevars_("f(x, *a, y=1, **k)", ["f"]),
                          ["x", "a", "k"])
-        if sys.version_info >= (3, 5):
-            self.assertEqual(freevars_("f(*a, *b, k=c, **d, **e)", ["f"]),
-                             ["a", "b", "c", "d", "e"])
+        self.assertEqual(freevars_("f(*a, *b, k=c, **d, **e)", ["f"]),
+                         ["a", "b", "c", "d", "e"])
 
         self.assertEqual(freevars_("True"), [])
         self.assertEqual(freevars_("'True'"), [])
diff --git a/setup.py b/setup.py
index 1409eacc521..6e65eafd118 100755
--- a/setup.py
+++ b/setup.py
@@ -10,8 +10,6 @@
 from distutils.command import config, build
 from distutils.core import Extension
 
-if sys.version_info < (3, 4):
-    sys.exit('Orange requires Python >= 3.4')
 
 try:
     import numpy
@@ -81,6 +79,9 @@
     'Intended Audience :: Developers',
 ]
 
+PYTHON_REQUIRES = ">=3.9"
+
+
 requirements = ['requirements-core.txt', 'requirements-gui.txt']
 
 
@@ -512,6 +513,7 @@ def setup_package():
         data_files=DATA_FILES,
         install_requires=INSTALL_REQUIRES,
         extras_require=EXTRAS_REQUIRE,
+        python_requires=PYTHON_REQUIRES,
         entry_points=ENTRY_POINTS,
         zip_safe=False,
         test_suite='Orange.tests.suite',