diff --git a/libutils/include/utils/String16.h b/libutils/include/utils/String16.h
index b48b90765..ec2a3241c 100644
--- a/libutils/include/utils/String16.h
+++ b/libutils/include/utils/String16.h
@@ -56,9 +56,6 @@ public:
     inline  const char16_t*     c_str() const;
     inline  const char16_t*     string() const;
 
-private:
-    static inline std::string   std_string(const String16& str);
-public:
             size_t              size() const;
     inline  bool                empty() const;
 
@@ -249,11 +246,6 @@ inline const char16_t* String16::string() const
     return mString;
 }
 
-inline std::string String16::std_string(const String16& str)
-{
-    return std::string(String8(str).c_str());
-}
-
 inline bool String16::empty() const
 {
     return length() == 0;
diff --git a/libutils/include/utils/String8.h b/libutils/include/utils/String8.h
index 9cef9f678..764b92a18 100644
--- a/libutils/include/utils/String8.h
+++ b/libutils/include/utils/String8.h
@@ -58,10 +58,6 @@ public:
     inline  const char*         c_str() const;
     inline  const char*         string() const;
 
-private:
-    static inline std::string   std_string(const String8& str);
-public:
-
     inline  size_t              size() const;
     inline  size_t              bytes() const;
     inline  bool                empty() const;
@@ -169,11 +165,6 @@ inline const char* String8::string() const
     return mString;
 }
 
-inline std::string String8::std_string(const String8& str)
-{
-    return std::string(str.c_str());
-}
-
 inline size_t String8::size() const
 {
     return length();