diff --git a/taglib/ape/apetag.cpp b/taglib/ape/apetag.cpp
index 7fb4a21c..bd7c62ab 100644
--- a/taglib/ape/apetag.cpp
+++ b/taglib/ape/apetag.cpp
@@ -323,11 +323,11 @@ bool APE::Tag::setComplexProperties(const String &key, const List<VariantMap> &v
 
     auto frontItems = List<Item>();
     auto backItems = List<Item>();
-    for(auto property : value) {
-      ByteVector data = property.value("description").value<String>().data(String::UTF8)
+    for(const auto &property : value) {
+      auto data = property.value("description").value<String>().data(String::UTF8)
                         .append('\0')
                         .append(property.value("data").value<ByteVector>());
-      String pictureType = property.value("pictureType").value<String>();
+      auto pictureType = property.value("pictureType").value<String>();
       Item item;
       item.setType(Item::Binary);
       item.setBinaryData(data);
diff --git a/taglib/asf/asftag.cpp b/taglib/asf/asftag.cpp
index adce2a2e..93fac8b6 100644
--- a/taglib/asf/asftag.cpp
+++ b/taglib/asf/asftag.cpp
@@ -432,7 +432,7 @@ bool ASF::Tag::setComplexProperties(const String &key, const List<VariantMap> &v
   if(uppercaseKey == "PICTURE") {
     removeItem("WM/Picture");
 
-    for(auto property : value) {
+    for(const auto &property : value) {
       ASF::Picture picture;
       picture.setPicture(property.value("data").value<ByteVector>());
       picture.setMimeType(property.value("mimeType").value<String>());
diff --git a/taglib/flac/flacfile.cpp b/taglib/flac/flacfile.cpp
index 40ed77d3..5387257d 100644
--- a/taglib/flac/flacfile.cpp
+++ b/taglib/flac/flacfile.cpp
@@ -200,8 +200,8 @@ bool FLAC::File::setComplexProperties(const String &key, const List<VariantMap>
   if(uppercaseKey == "PICTURE") {
     removePictures();
 
-    for(auto property : value) {
-      FLAC::Picture *picture = new FLAC::Picture;
+    for(const auto &property : value) {
+      auto picture = new FLAC::Picture;
       picture->setData(property.value("data").value<ByteVector>());
       picture->setMimeType(property.value("mimeType").value<String>());
       picture->setDescription(property.value("description").value<String>());
diff --git a/taglib/mp4/mp4tag.cpp b/taglib/mp4/mp4tag.cpp
index 4bfe9908..85fa6527 100644
--- a/taglib/mp4/mp4tag.cpp
+++ b/taglib/mp4/mp4tag.cpp
@@ -558,8 +558,8 @@ bool MP4::Tag::setComplexProperties(const String &key, const List<VariantMap> &v
   const String uppercaseKey = key.upper();
   if(uppercaseKey == "PICTURE") {
     CoverArtList pictures;
-    for(auto property : value) {
-      String mimeType = property.value("mimeType").value<String>();
+    for(const auto &property : value) {
+      auto mimeType = property.value("mimeType").value<String>();
       CoverArt::Format format;
       if(mimeType == "image/bmp") {
         format = CoverArt::BMP;
diff --git a/taglib/mpeg/id3v2/id3v2tag.cpp b/taglib/mpeg/id3v2/id3v2tag.cpp
index f3d9c71b..d3d02c3d 100644
--- a/taglib/mpeg/id3v2/id3v2tag.cpp
+++ b/taglib/mpeg/id3v2/id3v2tag.cpp
@@ -501,7 +501,7 @@ bool ID3v2::Tag::setComplexProperties(const String &key, const List<VariantMap>
   if(uppercaseKey == "PICTURE") {
     removeFrames("APIC");
 
-    for(auto property : value) {
+    for(const auto &property : value) {
       auto picture = new AttachedPictureFrame;
       picture->setPicture(property.value("data").value<ByteVector>());
       picture->setMimeType(property.value("mimeType").value<String>());
@@ -514,7 +514,7 @@ bool ID3v2::Tag::setComplexProperties(const String &key, const List<VariantMap>
   else if(uppercaseKey == "GENERALOBJECT") {
     removeFrames("GEOB");
 
-    for(auto property : value) {
+    for(const auto &property : value) {
       auto geob = new GeneralEncapsulatedObjectFrame;
       geob->setObject(property.value("data").value<ByteVector>());
       geob->setMimeType(property.value("mimeType").value<String>());
diff --git a/taglib/ogg/xiphcomment.cpp b/taglib/ogg/xiphcomment.cpp
index 2e0450a4..3769057d 100644
--- a/taglib/ogg/xiphcomment.cpp
+++ b/taglib/ogg/xiphcomment.cpp
@@ -272,8 +272,8 @@ bool Ogg::XiphComment::setComplexProperties(const String &key, const List<Varian
   if(uppercaseKey == "PICTURE") {
     removeAllPictures();
 
-    for(auto property : value) {
-      FLAC::Picture *picture = new FLAC::Picture;
+    for(const auto &property : value) {
+      auto picture = new FLAC::Picture;
       picture->setData(property.value("data").value<ByteVector>());
       picture->setMimeType(property.value("mimeType").value<String>());
       picture->setDescription(property.value("description").value<String>());