diff --git a/ippisite/ippidb/tests_utils.py b/ippisite/ippidb/tests_utils.py
index 0865028b482683279168d132f32822a20bc645c6..bf59015d9be616de248045867607c9bda862589a 100644
--- a/ippisite/ippidb/tests_utils.py
+++ b/ippisite/ippidb/tests_utils.py
@@ -129,13 +129,13 @@ class ConvertSMILESToSDFTestCase(TestCase):
         # the MOL version is also a valid regexp to validate arbitrary name in
         # the openbabel-generated version
         self.sdf = (
-            "1\n"
-            " OpenBabel[0-9]{11}D\n"
-            "\n"
-            "  1  0  0  0  0  0  0  0  0  0999 V2000\n"
-            "    0.0000    0.0000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0\n"
-            "M  END\n"
-            "\$\$\$\$\n"
+            r"1\n"
+            r" OpenBabel[0-9]{11}D\n"
+            r"\n"
+            r"  1  0  0  0  0  0  0  0  0  0999 V2000\n"
+            r"    0.0000    0.0000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0\n"
+            r"M  END\n"
+            r"\$\$\$\$\n"
         )
 
     def test_valid(self):