@@ -15,11 +15,11 @@
 #import "OFString.h"
 
 /**
  * A class for storing and modifying strings.
  */
-@interface OFMutableString: OFString
+@interface OFMutableString: OFString {}
 /**
  * Sets the OFString to the specified OFString.
  *
  * \param str An OFString to set the OFString to.
  */