diff --git a/db/btreecursor.cpp b/db/btreecursor.cpp
index f39d5bb..f81c2ec 100644
--- a/db/btreecursor.cpp
+++ b/db/btreecursor.cpp
@@ -52,7 +52,7 @@ namespace mongo {
             assert( !bucket.isNull() );
             const BtreeBucket<V> *b = bucket.btree<V>();
             int n = b->getN();
-            if( n == 0xffff ) { 
+            if( n == 0xffff || n == -1 ) { 
                 throw UserException(15850, "keyAt bucket deleted");
             }
             dassert( n >= 0 && n < 10000 );
diff --git a/jstests/removea.js b/jstests/removea.js
new file mode 100644
index 0000000..2ed3d60
--- /dev/null
+++ b/jstests/removea.js
@@ -0,0 +1,19 @@
+// Test removal of a substantial proportion of inserted elements.
+
+t = db.jstests_removea;
+t.drop();
+
+Random.setRandomSeed(1);
+
+for( v = 0; v < 2; ++v ) {
+    t.ensureIndex({a:1}, {v:v});
+    for( i = 0; i < 10000; ++i ) {
+        t.save( {a:i} );
+    }
+    toDrop = [];
+    for( i = 0; i < 10000; ++i ) {
+        toDrop.push( Random.randInt(10000) );
+    }
+    t.remove( {a:{$in:toDrop}} );
+    assert( !db.getLastError() );
+}