diff --git a/gerrit-antlr/BUILD b/gerrit-antlr/BUILD
index f4ce4c7..cb05469 100644
--- a/gerrit-antlr/BUILD
+++ b/gerrit-antlr/BUILD
@@ -2,7 +2,10 @@
 
 java_library(
     name = "query_exception",
-    srcs = ["src/main/java/com/google/gerrit/server/query/QueryParseException.java"],
+    srcs = [
+        "src/main/java/com/google/gerrit/server/query/QueryParseException.java",
+        "src/main/java/com/google/gerrit/server/query/QueryRequiresAuthException.java",
+    ],
     visibility = ["//visibility:public"],
 )
 
diff --git a/gerrit-antlr/src/main/java/com/google/gerrit/server/query/QueryRequiresAuthException.java b/gerrit-antlr/src/main/java/com/google/gerrit/server/query/QueryRequiresAuthException.java
new file mode 100644
index 0000000..a41e54f
--- /dev/null
+++ b/gerrit-antlr/src/main/java/com/google/gerrit/server/query/QueryRequiresAuthException.java
@@ -0,0 +1,32 @@
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.query;
+
+/**
+ * Exception thrown when a search query is invalid.
+ *
+ * <p><b>NOTE:</b> the message is visible to end users.
+ */
+public class QueryRequiresAuthException extends QueryParseException {
+  private static final long serialVersionUID = 1L;
+
+  public QueryRequiresAuthException(String message) {
+    super(message);
+  }
+
+  public QueryRequiresAuthException(String msg, Throwable why) {
+    super(msg, why);
+  }
+}
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeQueryBuilder.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeQueryBuilder.java
index 5c3e8c9..52009ad 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeQueryBuilder.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/ChangeQueryBuilder.java
@@ -71,6 +71,7 @@
 import com.google.gerrit.server.query.Predicate;
 import com.google.gerrit.server.query.QueryBuilder;
 import com.google.gerrit.server.query.QueryParseException;
+import com.google.gerrit.server.query.QueryRequiresAuthException;
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
@@ -388,23 +389,23 @@
       return asUser(userFactory.create(otherId));
     }
 
-    IdentifiedUser getIdentifiedUser() throws QueryParseException {
+    IdentifiedUser getIdentifiedUser() throws QueryRequiresAuthException {
       try {
         CurrentUser u = getUser();
         if (u.isIdentifiedUser()) {
           return u.asIdentifiedUser();
         }
-        throw new QueryParseException(NotSignedInException.MESSAGE);
+        throw new QueryRequiresAuthException(NotSignedInException.MESSAGE);
       } catch (ProvisionException e) {
-        throw new QueryParseException(NotSignedInException.MESSAGE, e);
+        throw new QueryRequiresAuthException(NotSignedInException.MESSAGE, e);
       }
     }
 
-    CurrentUser getUser() throws QueryParseException {
+    CurrentUser getUser() throws QueryRequiresAuthException {
       try {
         return self.get();
       } catch (ProvisionException e) {
-        throw new QueryParseException(NotSignedInException.MESSAGE, e);
+        throw new QueryRequiresAuthException(NotSignedInException.MESSAGE, e);
       }
     }
 
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/QueryChanges.java b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/QueryChanges.java
index f6ace3b..370bd21 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/query/change/QueryChanges.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/query/change/QueryChanges.java
@@ -29,6 +29,7 @@
 import com.google.gerrit.server.change.ChangeJson;
 import com.google.gerrit.server.index.change.ChangeField;
 import com.google.gerrit.server.query.QueryParseException;
+import com.google.gerrit.server.query.QueryRequiresAuthException;
 import com.google.gerrit.server.query.QueryResult;
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
@@ -36,8 +37,6 @@
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.List;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 import org.kohsuke.args4j.Option;
 
 public class QueryChanges implements RestReadView<TopLevelResource> {
@@ -110,15 +109,9 @@
     List<List<ChangeInfo>> out;
     try {
       out = query();
+    } catch (QueryRequiresAuthException e) {
+      throw new AuthException("Must be signed-in to use this operator");
     } catch (QueryParseException e) {
-      // This is a hack to detect an operator that requires authentication.
-      Pattern p =
-          Pattern.compile("^Error in operator (.*:self|is:watched|is:owner|is:reviewer|has:.*)$");
-      Matcher m = p.matcher(e.getMessage());
-      if (m.matches()) {
-        String op = m.group(1);
-        throw new AuthException("Must be signed-in to use " + op);
-      }
       throw new BadRequestException(e.getMessage(), e);
     }
     return out.size() == 1 ? out.get(0) : out;