diff --git a/compiler-rt/test/tsan/Linux/syscall.cpp b/compiler-rt/test/tsan/Linux/syscall.cpp
--- a/compiler-rt/test/tsan/Linux/syscall.cpp
+++ b/compiler-rt/test/tsan/Linux/syscall.cpp
@@ -6,7 +6,7 @@
 #include <sys/wait.h>
 
 int pipefd[2];
-char buf[10];
+unsigned long long buf[2];
 
 static void *thr(void *p) {
   barrier_wait(&barrier);