diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/config/ConfigUtil.java b/gerrit-server/src/main/java/com/google/gerrit/server/config/ConfigUtil.java
index 4878718d84..e124e486d0 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/config/ConfigUtil.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/config/ConfigUtil.java
@@ -23,7 +23,9 @@ import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Modifier;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
+import java.util.Map;
 import java.util.concurrent.TimeUnit;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -281,7 +283,7 @@ public class ConfigUtil {
         f.setAccessible(true);
         Object c = f.get(s);
         Object d = f.get(defaults);
-        if (!isString(t)) {
+        if (!isString(t) && !isCollectionOrMap(t)) {
           Preconditions.checkNotNull(d, "Default cannot be null for: " + n);
         }
         if (c == null || c.equals(d)) {
@@ -297,6 +299,9 @@ public class ConfigUtil {
             cfg.setBoolean(section, sub, n, (Boolean) c);
           } else if (t.isEnum()) {
             cfg.setEnum(section, sub, n, (Enum<?>) c);
+          } else if (isCollectionOrMap(t)) {
+            // TODO(davido): accept closure passed in from caller
+            continue;
           } else {
             throw new ConfigInvalidException("type is unknown: " + t.getName());
           }
@@ -337,7 +342,7 @@ public class ConfigUtil {
         String n = f.getName();
         f.setAccessible(true);
         Object d = f.get(defaults);
-        if (!isString(t)) {
+        if (!isString(t) && !isCollectionOrMap(t)) {
           Preconditions.checkNotNull(d, "Default cannot be null for: " + n);
         }
         if (isString(t)) {
@@ -357,6 +362,9 @@ public class ConfigUtil {
           }
         } else if (t.isEnum()) {
           f.set(s, cfg.getEnum(section, sub, n, (Enum<?>) d));
+        } else if (isCollectionOrMap(t)) {
+          // TODO(davido): accept closure passed in from caller
+          continue;
         } else {
           throw new ConfigInvalidException("type is unknown: " + t.getName());
         }
@@ -374,6 +382,11 @@ public class ConfigUtil {
     return s;
   }
 
+  private static boolean isCollectionOrMap(Class<?> t) {
+    return Collection.class.isAssignableFrom(t)
+        || Map.class.isAssignableFrom(t);
+  }
+
   private static boolean skipField(Field field) {
     int modifiers = field.getModifiers();
     return Modifier.isFinal(modifiers) || Modifier.isTransient(modifiers);
diff --git a/gerrit-server/src/test/java/com/google/gerrit/server/config/ConfigUtilTest.java b/gerrit-server/src/test/java/com/google/gerrit/server/config/ConfigUtilTest.java
index 28ae5757a4..12e6c35b84 100644
--- a/gerrit-server/src/test/java/com/google/gerrit/server/config/ConfigUtilTest.java
+++ b/gerrit-server/src/test/java/com/google/gerrit/server/config/ConfigUtilTest.java
@@ -27,6 +27,8 @@ import com.google.gerrit.extensions.client.Theme;
 import org.eclipse.jgit.lib.Config;
 import org.junit.Test;
 
+import java.util.List;
+import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
 public class ConfigUtilTest {
@@ -50,6 +52,8 @@ public class ConfigUtilTest {
     public String nd;
     public Theme t;
     public Theme td;
+    public List<String> list;
+    public Map<String, String> map;
     static SectionInfo defaults() {
       SectionInfo i = new SectionInfo();
       i.i = 1;