diff --git a/support/gecko/nsstring/src/lib.rs b/support/gecko/nsstring/src/lib.rs
index 8cb8d11ce7e..02352212938 100644
--- a/support/gecko/nsstring/src/lib.rs
+++ b/support/gecko/nsstring/src/lib.rs
@@ -559,6 +559,12 @@ macro_rules! define_string_types {
                     hdr: $StringRepr::new(ClassFlags::NULL_TERMINATED),
                 }
             }
+
+            /// Converts this String into a StringRepr, which will leak if the
+            /// repr is not passed to something that knows how to free it.
+            pub fn into_repr(mut self) -> $StringRepr {
+                mem::replace(&mut self.hdr, $StringRepr::new(ClassFlags::NULL_TERMINATED))
+            }
         }
 
         impl Drop for $String {