diff --git a/llvm/include/llvm/SandboxIR/Value.h b/llvm/include/llvm/SandboxIR/Value.h
index dd0bc76db3e37..8e50614d6a6d0 100644
--- a/llvm/include/llvm/SandboxIR/Value.h
+++ b/llvm/include/llvm/SandboxIR/Value.h
@@ -33,6 +33,7 @@ class IntrinsicInst;
 class Operator;
 class OverflowingBinaryOperator;
 class FPMathOperator;
+class Region;
 
 /// Iterator for the `Use` edges of a Value's users.
 /// \Returns a `Use` when dereferenced.