diff --git a/Eigen/src/Core/util/XprHelper.h b/Eigen/src/Core/util/XprHelper.h
index 7e6cb3381..f33b576ea 100644
--- a/Eigen/src/Core/util/XprHelper.h
+++ b/Eigen/src/Core/util/XprHelper.h
@@ -27,6 +27,8 @@
 #define EIGEN_XPRHELPER_H
 
 // just a workaround because GCC seems to not really like empty structs
+// FIXME: gcc 4.3 generates bad code when strict-aliasing is enabled
+// so currently we simply disable this optimization for gcc 4.3
 #if (defined __GNUG__) && !((__GNUC__==4) && (__GNUC_MINOR__==3))
   #define EIGEN_EMPTY_STRUCT_CTOR(X) \
     EIGEN_STRONG_INLINE X() {} \