diff --git a/scripts/tags.sh b/scripts/tags.sh
index 4e18ae5282a6..f667527ddff5 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -28,6 +28,13 @@ fi
 # ignore userspace tools
 ignore="$ignore ( -path ${tree}tools ) -prune -o"
 
+# gtags(1) refuses to index any file outside of its current working dir.
+# If gtags indexing is requested and the build output directory is not
+# the kernel source tree, index all files in absolute-path form.
+if [[ "$1" == "gtags" && -n "${tree}" ]]; then
+	tree=$(realpath "$tree")/
+fi
+
 # Detect if ALLSOURCE_ARCHS is set. If not, we assume SRCARCH
 if [ "${ALLSOURCE_ARCHS}" = "" ]; then
 	ALLSOURCE_ARCHS=${SRCARCH}
@@ -134,7 +141,7 @@ docscope()
 
 dogtags()
 {
-	all_target_sources | gtags -i -f -
+	all_target_sources | gtags -i -C "${tree:-.}" -f - "$PWD"
 }
 
 # Basic regular expressions with an optional /kind-spec/ for ctags and