diff --git a/indra/llcommon/tests/llsdserialize_test.cpp b/indra/llcommon/tests/llsdserialize_test.cpp
index c65a1d3ca0688042aa41e573f6498fde89330714..81de64930fbc265bb8ed31421a6556092962473d 100644
--- a/indra/llcommon/tests/llsdserialize_test.cpp
+++ b/indra/llcommon/tests/llsdserialize_test.cpp
@@ -1680,10 +1680,12 @@ namespace tut
             // in this case, the script is being written into a platform-
             // dependent temp directory! So locate indra/lib/python relative
             // to this C++ source file rather than the Python module.
+            // Use Python raw-string syntax so Windows pathname backslashes
+            // won't mislead Python's string scanner.
             import_llsd("import os.path\n"
                         "import sys\n"
                         "sys.path.insert(0,\n"
-                        "    os.path.join(os.path.dirname('" __FILE__ "'),\n"
+                        "    os.path.join(os.path.dirname(r'" __FILE__ "'),\n"
                         "                 os.pardir, os.pardir, 'lib', 'python'))\n"
                         "try:\n"
                         "    from llbase import llsd\n"