diff --git a/src/CheckIntegrityMan.cc b/src/CheckIntegrityMan.cc
deleted file mode 100644
index 1a7f438a..00000000
--- a/src/CheckIntegrityMan.cc
+++ /dev/null
@@ -1,53 +0,0 @@
-/* <!-- copyright */
-/*
- * aria2 - The high speed download utility
- *
- * Copyright (C) 2006 Tatsuhiro Tsujikawa
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- *
- * In addition, as a special exception, the copyright holders give
- * permission to link the code of portions of this program with the
- * OpenSSL library under certain conditions as described in each
- * individual source file, and distribute linked combinations
- * including the two.
- * You must obey the GNU General Public License in all respects
- * for all of the code used other than OpenSSL.  If you modify
- * file(s) with this exception, you may extend this exception to your
- * version of the file(s), but you are not obligated to do so.  If you
- * do not wish to do so, delete this exception statement from your
- * version.  If you delete this exception statement from all source
- * files in the program, then also delete it here.
- */
-/* copyright --> */
-#include "CheckIntegrityMan.h"
-#include "CheckIntegrityEntry.h"
-
-namespace aria2 {
-
-bool CheckIntegrityMan::isPicked(std::shared_ptr<RequestGroup> rg) {
-    return pickedEntry_ && rg && pickedEntry_->getRequestGroup() == rg.get();
-}
-
-bool CheckIntegrityMan::isQueued(std::shared_ptr<RequestGroup> rg) {
-    bool found = false;
-    for(auto& e : entries_) {
-        if(e && rg && e->getRequestGroup() == rg.get())
-            found = true;
-    }
-    return found;
-}
-
-}
diff --git a/src/CheckIntegrityMan.h b/src/CheckIntegrityMan.h
index 611910aa..2ea3b097 100644
--- a/src/CheckIntegrityMan.h
+++ b/src/CheckIntegrityMan.h
@@ -41,15 +41,8 @@
 namespace aria2 {
 
 class CheckIntegrityEntry;
-class RequestGroup;
 
-class CheckIntegrityMan : public SequentialPicker<CheckIntegrityEntry> {
-public:
-    bool isPicked(std::shared_ptr<RequestGroup> rg);
-    bool isQueued(std::shared_ptr<RequestGroup> rg);
-};
-
-// typedef SequentialPicker<CheckIntegrityEntry> CheckIntegrityMan;
+typedef SequentialPicker<CheckIntegrityEntry> CheckIntegrityMan;
 
 } // namespace aria2
 
diff --git a/src/Makefile.am b/src/Makefile.am
index d87a31c4..8614834a 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -39,7 +39,7 @@ SRCS =  \
 	CheckIntegrityCommand.cc CheckIntegrityCommand.h\
 	CheckIntegrityDispatcherCommand.cc CheckIntegrityDispatcherCommand.h\
 	CheckIntegrityEntry.cc CheckIntegrityEntry.h\
-	CheckIntegrityMan.cc CheckIntegrityMan.h\
+	CheckIntegrityMan.h\
 	Checksum.cc Checksum.h\
 	ChecksumCheckIntegrityEntry.cc ChecksumCheckIntegrityEntry.h\
 	ChunkChecksum.cc ChunkChecksum.h\
diff --git a/src/RequestGroupEntry.h b/src/RequestGroupEntry.h
index 7a1416c7..7484bf48 100644
--- a/src/RequestGroupEntry.h
+++ b/src/RequestGroupEntry.h
@@ -37,7 +37,6 @@
 
 #include "common.h"
 
-#include "Command.h"
 #include <memory>
 
 namespace aria2 {
diff --git a/src/RpcMethodImpl.cc b/src/RpcMethodImpl.cc
index cdb4fb1f..d808d83c 100644
--- a/src/RpcMethodImpl.cc
+++ b/src/RpcMethodImpl.cc
@@ -796,13 +796,22 @@ void gatherProgress(Dict* entryDict, const std::shared_ptr<RequestGroup>& group,
                              e->getBtRegistry()->get(group->getGID()), keys);
   }
 #endif // ENABLE_BITTORRENT
-  if (e && e->getCheckIntegrityMan()) {
-     if (e->getCheckIntegrityMan()->isPicked(group)) {
-        entryDict->put(KEY_VERIFIED_LENGTH, util::itos(e->getCheckIntegrityMan()->getPickedEntry()->getCurrentLength()));
-     }
-     if (e->getCheckIntegrityMan()->isQueued(group)) {
-        entryDict->put(KEY_VERIFY_PENDING, VLB_TRUE);
-     }
+  if (e->getCheckIntegrityMan()) {
+    if (e->getCheckIntegrityMan()->isPicked(
+            [&group](const CheckIntegrityEntry& ent) {
+              return ent.getRequestGroup() == group.get();
+            })) {
+      entryDict->put(
+          KEY_VERIFIED_LENGTH,
+          util::itos(
+              e->getCheckIntegrityMan()->getPickedEntry()->getCurrentLength()));
+    }
+    if (e->getCheckIntegrityMan()->isQueued(
+            [&group](const CheckIntegrityEntry& ent) {
+              return ent.getRequestGroup() == group.get();
+            })) {
+      entryDict->put(KEY_VERIFY_PENDING, VLB_TRUE);
+    }
   }
 }
 } // namespace
diff --git a/src/SequentialPicker.h b/src/SequentialPicker.h
index c464be78..eb4489b0 100644
--- a/src/SequentialPicker.h
+++ b/src/SequentialPicker.h
@@ -43,7 +43,7 @@
 namespace aria2 {
 
 template <typename T> class SequentialPicker {
-protected:
+private:
   std::deque<std::unique_ptr<T>> entries_;
   std::unique_ptr<T> pickedEntry_;
 
@@ -72,6 +72,21 @@ public:
   }
 
   size_t countEntryInQueue() const { return entries_.size(); }
+
+  bool isPicked(const std::function<bool(const T&)>& pred) const
+  {
+    return pickedEntry_ && pred(*pickedEntry_);
+  }
+
+  bool isQueued(const std::function<bool(const T&)>& pred) const
+  {
+    for (auto& e : entries_) {
+      if (pred(*e)) {
+        return true;
+      }
+    }
+    return false;
+  }
 };
 
 } // namespace aria2