diff --git a/taglib/riff/rifffile.cpp b/taglib/riff/rifffile.cpp
index 9aaf76ef..1d834b04 100644
--- a/taglib/riff/rifffile.cpp
+++ b/taglib/riff/rifffile.cpp
@@ -23,13 +23,15 @@
  *   http://www.mozilla.org/MPL/                                           *
  ***************************************************************************/
 
+#include <algorithm>
+#include <vector>
+
 #include <tbytevector.h>
 #include <tdebug.h>
 #include <tstring.h>
 
 #include "rifffile.h"
-#include <algorithm>
-#include <vector>
+#include "riffutils.h"
 
 using namespace TagLib;
 
@@ -175,7 +177,7 @@ void RIFF::File::setChunkData(const ByteVector &name, const ByteVector &data, bo
 
   // Couldn't find an existing chunk, so let's create a new one.
 
-  uint i =  d->chunks.size() - 1;
+  uint i = d->chunks.size() - 1;
   ulong offset = d->chunks[i].offset + d->chunks[i].size;
 
   // First we update the global size
@@ -189,7 +191,7 @@ void RIFF::File::setChunkData(const ByteVector &name, const ByteVector &data, bo
 
   // And update our internal structure
 
-  if (offset & 1) {
+  if(offset & 1) {
     d->chunks[i].padding = 1;
     offset++;
   }
@@ -231,19 +233,6 @@ void RIFF::File::removeChunk(const ByteVector &name)
 // private members
 ////////////////////////////////////////////////////////////////////////////////
 
-static bool isValidChunkID(const ByteVector &name)
-{
-  if(name.size() != 4) {
-    return false;
-  }
-  for(int i = 0; i < 4; i++) {
-    if(name[i] < 32 || name[i] > 127) {
-      return false;
-    }
-  }
-  return true;
-}
-
 void RIFF::File::read()
 {
   bool bigEndian = (d->endianness == BigEndian);
@@ -257,7 +246,7 @@ void RIFF::File::read()
     ByteVector chunkName = readBlock(4);
     uint chunkSize = readBlock(4).toUInt(bigEndian);
 
-    if(!isValidChunkID(chunkName)) {
+    if(!isValidChunkName(chunkName)) {
       debug("RIFF::File::read() -- Chunk '" + chunkName + "' has invalid ID");
       setValid(false);
       break;
diff --git a/taglib/riff/riffutils.h b/taglib/riff/riffutils.h
new file mode 100644
index 00000000..c9270dff
--- /dev/null
+++ b/taglib/riff/riffutils.h
@@ -0,0 +1,55 @@
+/***************************************************************************
+    copyright            : (C) 2015 by Tsuda Kageyu
+    email                : tsuda.kageyu@gmail.com
+ ***************************************************************************/
+
+/***************************************************************************
+ *   This library is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU Lesser General Public License version   *
+ *   2.1 as published by the Free Software Foundation.                     *
+ *                                                                         *
+ *   This library 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     *
+ *   Lesser General Public License for more details.                       *
+ *                                                                         *
+ *   You should have received a copy of the GNU Lesser General Public      *
+ *   License along with this library; if not, write to the Free Software   *
+ *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA         *
+ *   02110-1301  USA                                                       *
+ *                                                                         *
+ *   Alternatively, this file is available under the Mozilla Public        *
+ *   License Version 1.1.  You may obtain a copy of the License at         *
+ *   http://www.mozilla.org/MPL/                                           *
+ ***************************************************************************/
+
+#ifndef TAGLIB_RIFFUTILS_H
+#define TAGLIB_RIFFUTILS_H
+
+// THIS FILE IS NOT A PART OF THE TAGLIB API
+
+#ifndef DO_NOT_DOCUMENT  // tell Doxygen not to document this header
+
+namespace TagLib
+{
+  namespace RIFF
+  {
+    static bool isValidChunkName(const ByteVector &name)
+    {
+      if(name.size() != 4)
+        return false;
+
+      for(ByteVector::ConstIterator it = name.begin(); it != name.end(); ++it) {
+        const uchar c = static_cast<uchar>(*it);
+        if(c < 32 || 127 < c)
+          return false;
+      }
+
+      return true;
+    }
+  }
+}
+
+#endif
+
+#endif
diff --git a/taglib/riff/wav/infotag.cpp b/taglib/riff/wav/infotag.cpp
index dbd9395e..00d1f1c5 100644
--- a/taglib/riff/wav/infotag.cpp
+++ b/taglib/riff/wav/infotag.cpp
@@ -27,25 +27,13 @@
 #include <tfile.h>
 
 #include "infotag.h"
+#include "riffutils.h"
 
 using namespace TagLib;
 using namespace RIFF::Info;
 
 namespace
 {
-  inline bool isValidChunkID(const ByteVector &name)
-  {
-    if(name.size() != 4)
-      return false;
-
-    for(int i = 0; i < 4; i++) {
-      if(name[i] < 32 || name[i] > 127)
-        return false;
-    }
-
-    return true;
-  }
-
   const RIFF::Info::StringHandler defaultStringHandler;
   const RIFF::Info::StringHandler *stringHandler = &defaultStringHandler;
 }
@@ -197,7 +185,7 @@ String RIFF::Info::Tag::fieldText(const ByteVector &id) const
 void RIFF::Info::Tag::setFieldText(const ByteVector &id, const String &s)
 {
   // id must be four-byte long pure ascii string.
-  if(!isValidChunkID(id))
+  if(!isValidChunkName(id))
     return;
 
   if(!s.isEmpty())
@@ -258,7 +246,7 @@ void RIFF::Info::Tag::parse(const ByteVector &data)
       break;
 
     const ByteVector id = data.mid(p, 4);
-    if(isValidChunkID(id)) {
+    if(isValidChunkName(id)) {
       const String text = stringHandler->parse(data.mid(p + 8, size));
       d->fieldListMap[id] = text;
     }