diff --git a/buildsystem/check.py b/buildsystem/check.py
index 1f75a57c8ba0a1609821579dcdc2e45238e948f8..1aaf4188c0774cab1d27885cabef69355381984c 100644
--- a/buildsystem/check.py
+++ b/buildsystem/check.py
@@ -94,7 +94,7 @@ def filter_template_config(fin):
 def filter_template_ioparam(fin):
     defines = set()
     s = fin.read()
-    d = re.findall(r"add_param\(\"([a-zA-Z_][a-zA-Z_0-9]*)\"",s)
+    d = re.findall("add_param\(\"([a-zA-Z_][a-zA-Z_0-9]*)\"",s)
     for dd in d:
         defines.update([dd])