diff --git a/lib/asan/tests/asan_str_test.cpp b/lib/asan/tests/asan_str_test.cpp
index cc5bd2b..50e1ab4 100644
--- a/lib/asan/tests/asan_str_test.cpp
+++ b/lib/asan/tests/asan_str_test.cpp
@@ -454,7 +454,7 @@
   size_t from_size = Ident(20);
   char *from = MallocAndMemsetString(from_size);
   // Normal strncat calls.
-  strncat(to, from, 0);
+  strncat(to, from, 1);
   strncat(to, from, from_size);
   from[from_size - 1] = '\0';
   strncat(to, from, 2 * from_size);