diff --git a/artiq/test/lit/embedding/error_attr_constant.py b/artiq/test/lit/embedding/error_attr_constant.py
index d20913408..d78d4a65c 100644
--- a/artiq/test/lit/embedding/error_attr_constant.py
+++ b/artiq/test/lit/embedding/error_attr_constant.py
@@ -5,7 +5,7 @@ from artiq.language.core import *
 from artiq.language.types import *
 
 class c:
-    kernel_invariants = {'a'}
+    kernel_invariants = {"a"}
 
     def __init__(self):
         self.a = 1
diff --git a/artiq/test/lit/embedding/warning_invariant_2.py b/artiq/test/lit/embedding/warning_invariant_2.py
index 4160a29c0..b630b21d8 100644
--- a/artiq/test/lit/embedding/warning_invariant_2.py
+++ b/artiq/test/lit/embedding/warning_invariant_2.py
@@ -12,8 +12,8 @@ class c:
     def __repr__(self):
         return "<testbench.c object>"
 
-i1 = c({'a', 'b'})
-i2 = c({'a'})
+i1 = c({"a", "b"})
+i2 = c({"a"})
 
 @kernel
 def entrypoint():