diff --git a/clang-tools-extra/clangd/test/system-include-extractor.test b/clang-tools-extra/clangd/test/system-include-extractor.test
--- a/clang-tools-extra/clangd/test/system-include-extractor.test
+++ b/clang-tools-extra/clangd/test/system-include-extractor.test
@@ -63,7 +63,9 @@
 # CHECK:   "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:   "params": {
 # CHECK-NEXT:     "diagnostics": [],
-# CHECK-NEXT:     "uri": "file://INPUT_DIR/the-file.cpp",
+# Double-check that the diagnostics pertain to the intended file.
+# We don't match the path portion exactly to avoid issues around URL escaping.
+# CHECK-NEXT:     "uri": "file://{{.*}}/the-file.cpp",
 ---
 {"jsonrpc":"2.0","id":10000,"method":"shutdown"}
 ---