diff --git a/artiq/test/lit/lit.cfg b/artiq/test/lit/lit.cfg
index 8e03ad9f7..10497bdd0 100644
--- a/artiq/test/lit/lit.cfg
+++ b/artiq/test/lit/lit.cfg
@@ -27,7 +27,7 @@ not_ = "{} {}".format(sys.executable, os.path.join(root, "lit", "not.py"))
 config.substitutions.append( ("%not", not_) )
 
 if os.name == "posix":
-    support_lib = os.getenv("LIBARTIQ_SUPPORT"):
+    support_lib = os.getenv("LIBARTIQ_SUPPORT")
     if not support_lib:
         support_build = os.path.join(root, "libartiq_support")
         if subprocess.call(["rustc", os.path.join(support_build, "lib.rs"),