diff --git a/ConfigureChecks.cmake b/ConfigureChecks.cmake
index 5a8d9f1d..b8f19e84 100644
--- a/ConfigureChecks.cmake
+++ b/ConfigureChecks.cmake
@@ -14,7 +14,7 @@ include(CheckCXXSourceCompiles)
 #check for libz using the cmake supplied FindZLIB.cmake
 
 IF(ZLIB_FOUND)
-	SET(HAVE_LIBZ 1)
+	SET(HAVE_ZLIB 1)
 ELSE(ZLIB_FOUND)
-	SET(HAVE_LIBZ 0)
+	SET(HAVE_ZLIB 0)
 ENDIF(ZLIB_FOUND)
diff --git a/config-taglib.h.cmake b/config-taglib.h.cmake
index a3439996..cb35884f 100644
--- a/config-taglib.h.cmake
+++ b/config-taglib.h.cmake
@@ -4,4 +4,4 @@
    Otherwise please prefer adding to the relevant config-foo.h.cmake file,
    to minimize recompilations and increase modularity. */
 /* Define if you have libz */
-#cmakedefine   HAVE_LIBZ 1
+#cmakedefine   HAVE_ZLIB 1
diff --git a/taglib/fileref.h b/taglib/fileref.h
index fa435eb9..5044c004 100644
--- a/taglib/fileref.h
+++ b/taglib/fileref.h
@@ -88,6 +88,7 @@ namespace TagLib {
     class FileTypeResolver
     {
     public:
+      virtual ~FileTypeResolver() {}
       /*!
        * This method must be overriden to provide an additional file type
        * resolver.  If the resolver is able to determine the file type it should
diff --git a/taglib/mpeg/id3v1/id3v1tag.h b/taglib/mpeg/id3v1/id3v1tag.h
index 0b238bdd..8aa3b71c 100644
--- a/taglib/mpeg/id3v1/id3v1tag.h
+++ b/taglib/mpeg/id3v1/id3v1tag.h
@@ -55,6 +55,7 @@ namespace TagLib {
     class StringHandler
     {
     public:
+      virtual ~StringHandler(){}
       /*!
        * Decode a string from \a data.  The default implementation assumes that
        * \a data is an ISO-8859-1 (Latin1) character array.