diff --git a/Eigen/src/Core/util/Macros.h b/Eigen/src/Core/util/Macros.h
index 733d3403e..bfd6ba7de 100644
--- a/Eigen/src/Core/util/Macros.h
+++ b/Eigen/src/Core/util/Macros.h
@@ -82,6 +82,8 @@
     #define EIGEN_ALIGN_BYTES 32
   #endif
   #define EIGEN_ALIGN 1
+#else
+  #define EIGEN_ALIGN 0
 #endif
 
 // EIGEN_ALIGN_STATICALLY is the true test whether we want to align arrays on the stack or not. It takes into account both the user choice to explicitly disable