diff --git a/base-common/duneci-install-module b/base-common/duneci-install-module
index d2ae61633edace02786649070c72b7481ecf2cb6..f2bf90a7497a2e772702d8258cfde1460f3f38ad 100755
--- a/base-common/duneci-install-module
+++ b/base-common/duneci-install-module
@@ -74,7 +74,7 @@ opts="${DUNECI_OPTS:-/duneci/opts.gcc}"
 
 (
     cd "${module}"
-    git_branch=$(git symbolic-ref HEAD)
+    git_branch=$(git symbolic-ref HEAD 2>/dev/null || echo "(unknown)")
     git_branch="${git_branch#refs/heads/}"
     echo
     echo "Installing ${module}; branch ${git_branch}"