diff -ur mpdecimal-2.5.0/libmpdec++/decimal.hh mpdecimal-2.5.0/libmpdec++/decimal.hh
--- mpdecimal-2.5.0/libmpdec++/decimal.hh     2020-06-27 21:41:49.000000000 +0200
+++ mpdecimal-2.5.0/libmpdec++/decimal.hh     2020-08-05 13:39:26.570886524 +0200
@@ -47,9 +47,13 @@
 #include "mpdecimal.h"


+#undef iscanonical /* math.h */
 #undef isfinite    /* math.h */
+#undef isinf       /* math.h */
 #undef isnan       /* math.h */
+#undef isnormal    /* math.h */
 #undef issubnormal /* math.h */
+#undef iszero      /* math.h */
 #undef isspecial   /* ctype.h */

 #ifdef _MSC_VER