diff --git a/indexer/CompilationDatabase.cc b/indexer/CompilationDatabase.cc
index aaa29ad7..57e3fb10 100644
--- a/indexer/CompilationDatabase.cc
+++ b/indexer/CompilationDatabase.cc
@@ -535,6 +535,28 @@ compdb::File compdb::File::open(const StdPath &path,
   if (fileSizeError) {
     return compdbFile;
   }
+  if (validationOptions.tryDetectOutOfProjectRoot) {
+    auto dirPath = path.lexically_normal();
+    while (dirPath.has_parent_path() && dirPath.parent_path() != dirPath) {
+      dirPath = dirPath.parent_path();
+      auto maybeGitDirPath = dirPath / ".git";
+      std::error_code error;
+      auto status = std::filesystem::status(maybeGitDirPath, error);
+      if (!error && status.type() == std::filesystem::file_type::directory) {
+        auto cwd = std::filesystem::current_path();
+        if (cwd != dirPath) {
+          spdlog::warn(
+              "found .git directory in {} but current working directory is {};"
+              " did you invoke scip-clang from the project root?",
+              dirPath.string(), cwd.string());
+          spdlog::info(
+              "invoking scip-clang from a directory other than the project root"
+              " may lead to incorrect indexing results");
+          break;
+        }
+      }
+    }
+  }
   compdbFile._sizeInBytes = size;
   compdbFile._commandCount = validateAndCountJobs(
       compdbFile._sizeInBytes, compdbFile.file, validationOptions);
diff --git a/indexer/CompilationDatabase.h b/indexer/CompilationDatabase.h
index 1c25c36c..6e635c4d 100644
--- a/indexer/CompilationDatabase.h
+++ b/indexer/CompilationDatabase.h
@@ -29,6 +29,7 @@ namespace compdb {
 
 struct ValidationOptions {
   bool checkDirectoryPathsAreAbsolute;
+  bool tryDetectOutOfProjectRoot;
 };
 
 class File {
diff --git a/indexer/Driver.cc b/indexer/Driver.cc
index 846bd59d..c8872bb6 100644
--- a/indexer/Driver.cc
+++ b/indexer/Driver.cc
@@ -1227,8 +1227,9 @@ class Driver {
     StdPath compdbStdPath{this->compdbPath().asStringRef()};
     auto compdbFile = compdb::File::openAndExitOnErrors(
         compdbStdPath,
-        compdb::ValidationOptions{.checkDirectoryPathsAreAbsolute =
-                                      !this->options.isTesting});
+        compdb::ValidationOptions{
+            .checkDirectoryPathsAreAbsolute = !this->options.isTesting,
+            .tryDetectOutOfProjectRoot = !this->options.isTesting});
     this->compdbCommandCount = compdbFile.commandCount();
     this->options.numWorkers =
         std::min(this->compdbCommandCount, this->numWorkers());
diff --git a/indexer/Worker.cc b/indexer/Worker.cc
index 2c2b9b05..0b91ecff 100644
--- a/indexer/Worker.cc
+++ b/indexer/Worker.cc
@@ -144,7 +144,8 @@ Worker::Worker(WorkerOptions &&options)
   case WorkerMode::Compdb: {
     auto compdbFile = compdb::File::openAndExitOnErrors(
         this->options.compdbPath,
-        compdb::ValidationOptions{.checkDirectoryPathsAreAbsolute = true});
+        compdb::ValidationOptions{.checkDirectoryPathsAreAbsolute = true,
+                                  .tryDetectOutOfProjectRoot = true});
     compdb::ResumableParser parser{};
     parser.initialize(compdbFile,
                       compdb::ParseOptions::create(
diff --git a/test/test_main.cc b/test/test_main.cc
index 953c45be..823d776f 100644
--- a/test/test_main.cc
+++ b/test/test_main.cc
@@ -175,7 +175,8 @@ TEST_CASE("COMPDB_PARSING") {
 
     auto compdbFile = compdb::File::openAndExitOnErrors(
         jsonFilePath,
-        compdb::ValidationOptions{.checkDirectoryPathsAreAbsolute = false});
+        compdb::ValidationOptions{.checkDirectoryPathsAreAbsolute = false,
+                                  .tryDetectOutOfProjectRoot = false});
     if (!compdbFile.file) {
       spdlog::error("missing JSON file at path {}", jsonFilePath.c_str());
       REQUIRE(compdbFile.file);