diff --git a/llvm/include/llvm/IR/BasicBlock.h b/llvm/include/llvm/IR/BasicBlock.h
index c24f01fe26cc8..533808e0666d5 100644
--- a/llvm/include/llvm/IR/BasicBlock.h
+++ b/llvm/include/llvm/IR/BasicBlock.h
@@ -68,7 +68,7 @@ class BasicBlock final : public Value, // Basic blocks are data objects also
   // Allow Function to renumber blocks.
   friend class Function;
   /// Per-function unique number.
-  unsigned Number = -1u;
+  unsigned Number = ~0u;
 
   friend class BlockAddress;
   friend class SymbolTableListTraits<BasicBlock>;