diff --git a/lib/src/revset.pest b/lib/src/revset.pest
index 2f23c17e6..eaf771353 100644
--- a/lib/src/revset.pest
+++ b/lib/src/revset.pest
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-identifier = @{ (ASCII_ALPHANUMERIC | "@" | "/" | ".")+ } 
+identifier = @{ (ASCII_ALPHANUMERIC | "_" | "@" | "/" | ".")+ } 
 symbol = {
   identifier
   | literal_string