diff --git a/blas/xerbla.cpp b/blas/xerbla.cpp
index 0d57710fe..dd39a5244 100644
--- a/blas/xerbla.cpp
+++ b/blas/xerbla.cpp
@@ -1,7 +1,7 @@
 
 #include <iostream>
 
-#if (defined __GNUC__)
+#if (defined __GNUC__) && (!defined __MINGW32__) && (!defined __CYGWIN__)
 #define EIGEN_WEAK_LINKING __attribute__ ((weak))
 #else
 #define EIGEN_WEAK_LINKING
diff --git a/unsupported/test/mpreal/mpreal.h b/unsupported/test/mpreal/mpreal.h
index dddda7dd9..7d6f4e79f 100644
--- a/unsupported/test/mpreal/mpreal.h
+++ b/unsupported/test/mpreal/mpreal.h
@@ -57,7 +57,8 @@
 #include <limits>
 
 // Options
-#define MPREAL_HAVE_INT64_SUPPORT               // Enable int64_t support if possible. Available only for MSVC 2010 & GCC. 
+// FIXME HAVE_INT64_SUPPORT leads to clashes with long int and int64_t on some systems.
+//#define MPREAL_HAVE_INT64_SUPPORT               // Enable int64_t support if possible. Available only for MSVC 2010 & GCC.
 #define MPREAL_HAVE_MSVC_DEBUGVIEW              // Enable Debugger Visualizer for "Debug" builds in MSVC.
 #define MPREAL_HAVE_DYNAMIC_STD_NUMERIC_LIMITS  // Enable extended std::numeric_limits<mpfr::mpreal> specialization.
                                                 // Meaning that "digits", "round_style" and similar members are defined as functions, not constants.