diff --git a/compiler-rt/lib/scudo/standalone/secondary.h b/compiler-rt/lib/scudo/standalone/secondary.h
--- a/compiler-rt/lib/scudo/standalone/secondary.h
+++ b/compiler-rt/lib/scudo/standalone/secondary.h
@@ -232,7 +232,7 @@
     const u32 MaxCount = atomic_load_relaxed(&MaxEntriesCount);
     bool Found = false;
     CachedBlock Entry;
-    uptr HeaderPos;
+    uptr HeaderPos = 0;
     {
       ScopedLock L(Mutex);
       if (EntriesCount == 0)