diff --git a/libutils/include/utils/String16.h b/libutils/include/utils/String16.h
index 1fa3723..c713576 100644
--- a/libutils/include/utils/String16.h
+++ b/libutils/include/utils/String16.h
@@ -59,7 +59,6 @@
                                 ~String16();
 
     inline  const char16_t*     c_str() const;
-    inline  const char16_t*     string() const;
 
             size_t              size() const;
     inline  bool                empty() const;
@@ -188,6 +187,14 @@
 
     template <size_t N>
     explicit constexpr String16(const StaticData<N>& s) : mString(s.data) {}
+
+// These symbols are for potential backward compatibility with prebuilts. To be removed.
+#ifdef ENABLE_STRING16_OBSOLETE_METHODS
+public:
+#else
+private:
+#endif
+    inline  const char16_t*     string() const;
 };
 
 // String16 can be trivially moved using memcpy() because moving does not
diff --git a/libutils/include/utils/String8.h b/libutils/include/utils/String8.h
index 0b92f5b..6d25072 100644
--- a/libutils/include/utils/String8.h
+++ b/libutils/include/utils/String8.h
@@ -65,7 +65,6 @@
     static String8              formatV(const char* fmt, va_list args);
 
     inline  const char*         c_str() const;
-    inline  const char*         string() const;
 
     inline  size_t              size() const;
     inline  size_t              bytes() const;
@@ -155,6 +154,7 @@
 #else
 private:
 #endif
+    inline  const char*         string() const;
     inline  bool                isEmpty() const;
 };