diff --git a/runtime/mirror/string.cc b/runtime/mirror/string.cc
index 3f35210..d4f11b2 100644
--- a/runtime/mirror/string.cc
+++ b/runtime/mirror/string.cc
@@ -138,9 +138,7 @@
 }
 
 String* String::AllocFromModifiedUtf8(Thread* self, const char* utf) {
-  if (UNLIKELY(utf == nullptr)) {
-    return nullptr;
-  }
+  DCHECK(utf != nullptr);
   size_t char_count = CountModifiedUtf8Chars(utf);
   return AllocFromModifiedUtf8(self, char_count, utf);
 }