diff --git a/jstests/mmap_v1/capped2.js b/jstests/mmap_v1/capped2.js
index 65bb82f4c07..3ecb6c219b0 100644
--- a/jstests/mmap_v1/capped2.js
+++ b/jstests/mmap_v1/capped2.js
@@ -48,13 +48,21 @@ function checkDecreasing( i ) {
 for( i = 0 ;; ++i ) {
     debug( "capped 2: " + i );
     tzz.insert( val[ i ] );
-    if ( tzz.count() == 0 ) {
+    var err = db.getLastError();
+    if ( err ) {
+        debug(err);
+        debug(tzz.count());
     	assert( i > 100, "K" );
         break;
     }
     checkIncreasing( i );
 }
 
+// drop and recreate. Test used to rely on the last insert emptying the collection, which it no
+// longer does now that we rollback on failed inserts.
+tzz.drop();
+db._dbCommand( { create: "capped2", capped: true, size: 1000, $nExtents: 11, autoIndexId: false } );
+
 for( i = 600 ; i >= 0 ; --i ) {
     debug( "capped 2: " + i );
     tzz.insert( val[ i ] );
diff --git a/src/mongo/db/storage/mmap_v1/dur_recovery_unit.cpp b/src/mongo/db/storage/mmap_v1/dur_recovery_unit.cpp
index 83209a7fa9b..9443c01b284 100644
--- a/src/mongo/db/storage/mmap_v1/dur_recovery_unit.cpp
+++ b/src/mongo/db/storage/mmap_v1/dur_recovery_unit.cpp
@@ -39,7 +39,7 @@
 #include "mongo/util/log.h"
 
 // Remove once we are ready to enable
-#define ROLLBACK_ENABLED 0
+#define ROLLBACK_ENABLED 1
 
 namespace mongo {