diff --git a/base/include/hidl/HidlSupport.h b/base/include/hidl/HidlSupport.h
index 106fb02..7477352 100644
--- a/base/include/hidl/HidlSupport.h
+++ b/base/include/hidl/HidlSupport.h
@@ -128,6 +128,8 @@
     hidl_string(const hidl_string &);
     // copy from a C-style string.
     hidl_string(const char *);
+    // copy the first length characters from a C-style string.
+    hidl_string(const char *, size_t length);
     // copy from an std::string.
     hidl_string(const std::string &);