1 files changed, 7 insertions, 0 deletions
diff --git a/src/other_tools/repo_map/repos_to_setup_map.cpp b/src/other_tools/repo_map/repos_to_setup_map.cpp
index d8bfe3a3..27c39a77 100644
--- a/src/other_tools/repo_map/repos_to_setup_map.cpp
+++ b/src/other_tools/repo_map/repos_to_setup_map.cpp
@@ -112,6 +112,13 @@ void GitCheckout(ExpressionPtr const& repo_desc,
                                             ? repo_desc_subdir->String()
                                             : "")
                       .lexically_normal();
+    if (subdir.is_absolute()) {
+        (*logger)(fmt::format("GitCheckout: Expected field \"subdir\" to be a "
+                              "relative path, but found {}",
+                              subdir.string()),
+                  /*fatal=*/true);
+        return;
+    }
     // check optional mirrors
     auto repo_desc_mirrors = repo_desc->Get("mirrors", Expression::list_t{});
     std::vector<std::string> mirrors{};