diff --git a/Eigen/src/Array/Array.h b/Eigen/src/Array/Array.h
index 30d5529fd..8cf1ae3fb 100644
--- a/Eigen/src/Array/Array.h
+++ b/Eigen/src/Array/Array.h
@@ -51,7 +51,7 @@ class Array
     using Base::m_storage;
   public:
     enum { NeedsToAlign = (!(Options&DontAlign))
-                          && SizeAtCompileTime!=Dynamic && ((sizeof(Scalar)*SizeAtCompileTime)%16)==0 };
+                          && SizeAtCompileTime!=Dynamic && ((static_cast<int>(sizeof(Scalar))*SizeAtCompileTime)%16)==0 };
     EIGEN_MAKE_ALIGNED_OPERATOR_NEW_IF(NeedsToAlign)
 
     using Base::base;