diff --git a/build.gradle b/build.gradle
index b3826ab..248dba8 100644
--- a/build.gradle
+++ b/build.gradle
@@ -67,15 +67,15 @@ tasks.withType(Javadoc) {
 
 checkstyle {
   toolVersion '7.8.1'
-  configFile file("config/checkstyle/checkstyle.xml")
+  configFile file("$project.rootDir/config/checkstyle/checkstyle.xml")
   sourceSets = [sourceSets.main]
   showViolations = true
   ignoreFailures = false
   maxWarnings = 0
   //reportsDir = file("$project.rootDir/reports/checkstyle/$project.name")
   configProperties = [
-          'checkstyle.header.file': "config/checkstyle/copyright_header.txt",
-          'suppressionFile': "config/checkstyle/suppressions.xml"
+          'checkstyle.header.file': "$project.rootDir/config/checkstyle/copyright_header.txt",
+          'suppressionFile': "$project.rootDir/config/checkstyle/suppressions.xml"
   ]
 }
 
diff --git a/src/main/java/org/intermine/client/lists/Lists.java b/src/main/java/org/intermine/client/lists/Lists.java
index 89c9670..08b2a21 100644
--- a/src/main/java/org/intermine/client/lists/Lists.java
+++ b/src/main/java/org/intermine/client/lists/Lists.java
@@ -95,7 +95,7 @@ public static ItemList parseListCreationInfo(ServiceFactory factory,
             if (jo.has("unmatchedIdentifiers")) {
                 JSONArray badIds = jo.getJSONArray("unmatchedIdentifiers");
                 for (int i = 0; i < badIds.length(); i++) {
-                    il.addUnmatchedId(badIds.getString(i));
+                    il.addUnmatchedId(badIds.optString(i));
                 }
             }
             return il;