diff --git a/test/test_cstdfloat.cpp b/test/test_cstdfloat.cpp
index 5fc616c9b..28d64416a 100644
--- a/test/test_cstdfloat.cpp
+++ b/test/test_cstdfloat.cpp
@@ -55,6 +55,20 @@
 // the functionality of <cmath>, I/O stream operations, and <complex>
 // functions for boost::float128_t.
 
+// For some reason the (x != x) check fails on Mingw:
+#if !defined(__MINGW64__)
+#define TEST_CSTDFLOAT_SANITY_CHECK_NAN(the_digits)                                                  \
+  {                                                                                                  \
+    using std::sqrt;                                                                                 \
+    const float_type x = sqrt(float_type(test_cstdfloat::minus_one));                                \
+    const bool the_nan_test = (   std::numeric_limits<float_type>::has_quiet_NaN                     \
+                               && (x != x));                                                         \
+    BOOST_CHECK_EQUAL( the_nan_test, true );                                                         \
+  }  
+#else
+#define TEST_CSTDFLOAT_SANITY_CHECK_NAN(the_digits)                                                  
+#endif
+
 #define TEST_CSTDFLOAT_SANITY_CHECK(the_digits)                                                      \
 void sanity_check_##the_digits##_func()                                                              \
 {                                                                                                    \
@@ -89,13 +103,7 @@ void sanity_check_##the_digits##_func()
                                && (x == std::numeric_limits<float_type>::infinity()));               \
     BOOST_CHECK_EQUAL( the_inf_test, true );                                                         \
   }                                                                                                  \
-  {                                                                                                  \
-    using std::sqrt;                                                                                 \
-    const float_type x = sqrt(float_type(test_cstdfloat::minus_one));                                \
-    const bool the_nan_test = (   std::numeric_limits<float_type>::has_quiet_NaN                     \
-                               && (x != x));                                                         \
-    BOOST_CHECK_EQUAL( the_nan_test, true );                                                         \
-  }                                                                                                  \
+  TEST_CSTDFLOAT_SANITY_CHECK_NAN(the_digits)\
   {                                                                                                  \
     const bool the_lim_test =                                                                        \
       (std::numeric_limits<boost::floatmax_t>::digits >= std::numeric_limits<float_type>::digits);   \