diff --git a/src/libfuzzer/libfuzzer_mutator.cc b/src/libfuzzer/libfuzzer_mutator.cc
index dfb86ef..34d144c 100644
--- a/src/libfuzzer/libfuzzer_mutator.cc
+++ b/src/libfuzzer/libfuzzer_mutator.cc
@@ -89,13 +89,8 @@ std::string Mutator::MutateString(const std::string& value,
   // any 8 bit types.
   if (!std::uniform_int_distribution<uint16_t>(0, 20)(*random())) return {};
   std::string result = value;
-  std::string::size_type new_size = 0;
-  if (size_increase_hint >= 0 || static_cast<std::string::size_type>(
-                                     -size_increase_hint) <= value.size()) {
-    new_size = value.size() + size_increase_hint;
-  }
-  result.resize(new_size);
-  if (result.empty()) result.push_back(0);
+  int new_size = value.size() + size_increase_hint;
+  result.resize(std::max(1, new_size));
   result.resize(LLVMFuzzerMutate(reinterpret_cast<uint8_t*>(&result[0]),
                                  value.size(), result.size()));
   return result;