diff --git a/src/main/java/com/googlesource/gerrit/plugins/reviewers/config/ReviewerFilterCollection.java b/src/main/java/com/googlesource/gerrit/plugins/reviewers/config/ReviewerFilterCollection.java
index 91b49e8..c0babc4 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/reviewers/config/ReviewerFilterCollection.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/reviewers/config/ReviewerFilterCollection.java
@@ -18,6 +18,7 @@
 import static com.googlesource.gerrit.plugins.reviewers.config.ForProject.KEY_REVIEWER;
 import static com.googlesource.gerrit.plugins.reviewers.config.ForProject.SECTION_FILTER;
 
+import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
@@ -89,7 +90,9 @@
    * ValidationError to the ValidationError.Sink and returns the error. */
   private Optional<String> checkForErrors(String filterQuery) {
     try {
-      queryValidator.validateQuery(filterQuery);
+      if (!Strings.isNullOrEmpty(filterQuery) && !"*".equals(filterQuery)) {
+        queryValidator.validateQuery(filterQuery);
+      }
     } catch (QueryParseException qpe) {
       validationErrorSink.ifPresent(ves -> ves.error(ValidationError.create(qpe.getMessage())));
       return Optional.of(qpe.getMessage());