diff --git a/xwords4/android/app/src/main/java/org/eehouse/android/xw4/GameLock.java b/xwords4/android/app/src/main/java/org/eehouse/android/xw4/GameLock.java
index d060d0e06..27a68b653 100644
--- a/xwords4/android/app/src/main/java/org/eehouse/android/xw4/GameLock.java
+++ b/xwords4/android/app/src/main/java/org/eehouse/android/xw4/GameLock.java
@@ -26,6 +26,8 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.Stack;
 
+import android.support.annotation.NonNull;
+
 // Implements read-locks and write-locks per game.  A read lock is
 // obtainable when other read locks are granted but not when a
 // write lock is.  Write-locks are exclusive.
@@ -156,24 +158,30 @@ public class GameLock implements AutoCloseable {
         return this;
     }
 
+    @NonNull
     public GameLock lock() throws InterruptedException
     {
         if ( BuildConfig.DEBUG ) {
             DbgUtils.assertOnUIThread( false );
         }
-        return lockImpl( Long.MAX_VALUE, false );
+        GameLock result = lockImpl( Long.MAX_VALUE, false );
+        Assert.assertNotNull( result );
+        return result;
     }
 
-    public GameLock lockRO() throws InterruptedException
-    {
-        if ( BuildConfig.DEBUG ) {
-            DbgUtils.assertOnUIThread( false );
-        }
-        return lockImpl( Long.MAX_VALUE, true );
-    }
+    // @NonNull
+    // public GameLock lockRO() throws InterruptedException
+    // {
+    //     if ( BuildConfig.DEBUG ) {
+    //         DbgUtils.assertOnUIThread( false );
+    //     }
+    //     GameLock result = lockImpl( Long.MAX_VALUE, true );
+    //     Assert.assertNotNull( result );
+    //     return result;
+    // }
 
     // Version that's allowed to return null -- if maxMillis > 0
-    public GameLock lock( long maxMillis )
+    public GameLock lock( long maxMillis ) throws GameLockedException
     {
         Assert.assertTrue( maxMillis <= THROW_TIME );
         GameLock result = null;
diff --git a/xwords4/android/app/src/main/java/org/eehouse/android/xw4/GameUtils.java b/xwords4/android/app/src/main/java/org/eehouse/android/xw4/GameUtils.java
index 1a0fad4ca..370672797 100644
--- a/xwords4/android/app/src/main/java/org/eehouse/android/xw4/GameUtils.java
+++ b/xwords4/android/app/src/main/java/org/eehouse/android/xw4/GameUtils.java
@@ -1007,6 +1007,8 @@ public class GameUtils {
                         }
                     }
                 }
+            } catch ( GameLock.GameLockedException gle ) {
+                Log.e( TAG, "feedMessage(): game locked; dropping message" );
             }
         }
         return draw;