diff --git a/runtime/bin/typed_data_utils.cc b/runtime/bin/typed_data_utils.cc
index 7d4169273da..c07fb603cee 100644
--- a/runtime/bin/typed_data_utils.cc
+++ b/runtime/bin/typed_data_utils.cc
@@ -56,8 +56,9 @@ intptr_t TypedDataScope::size_in_bytes() const {
 }
 
 const char* TypedDataScope::GetScopedCString() const {
-  char* buf = reinterpret_cast<char*>(Dart_ScopeAllocate(size_in_bytes()));
+  char* buf = reinterpret_cast<char*>(Dart_ScopeAllocate(size_in_bytes() + 1));
   strncpy(buf, GetCString(), size_in_bytes());
+  buf[size_in_bytes()] = '\0';
   return buf;
 }
 
diff --git a/tests/standalone/io/io_override_test.dart b/tests/standalone/io/io_override_test.dart
index 79d3925478c..816b54c7401 100644
--- a/tests/standalone/io/io_override_test.dart
+++ b/tests/standalone/io/io_override_test.dart
@@ -293,8 +293,19 @@ globalIOOverridesZoneTest() {
   Expect.isTrue(dir is Directory);
 }
 
+class EmptyOverride extends IOOverrides {}
+
+void emptyIOOverride() {
+  IOOverrides.runWithIOOverrides(
+    () => Expect.equals(
+        FileSystemEntity.typeSync('/'), FileSystemEntityType.directory),
+    EmptyOverride(),
+  );
+}
+
 main() async {
   await ioOverridesRunTest();
   globalIOOverridesTest();
   globalIOOverridesZoneTest();
+  emptyIOOverride();
 }