diff -up build/pkgs/giac/spkg-configure.m4.orig build/pkgs/giac/spkg-configure.m4
--- build/pkgs/giac/spkg-configure.m4.orig	2022-09-19 16:38:18.000000000 -0600
+++ build/pkgs/giac/spkg-configure.m4	2023-01-15 19:56:31.030581488 -0700
@@ -21,7 +21,7 @@ SAGE_SPKG_CONFIGURE([giac], [
        AC_CHECK_HEADER([giac/giac.h], [
         AC_SEARCH_LIBS([ConvertUTF16toUTF8], [giac], [
         ], [sage_spkg_install_giac=yes])
-       ], [sage_spkg_install_giac=yes])
+       ], [sage_spkg_install_giac=yes], [typedef unsigned char uchar;])
        m4_popdef([GIAC_MIN_VERSION])
        m4_popdef([GIAC_MAX_VERSION])
     ])
diff -up configure.orig configure
--- configure.orig	2023-01-15 19:55:21.828822178 -0700
+++ configure	2023-01-15 19:58:12.425759949 -0700
@@ -26479,7 +26479,8 @@ printf "%s\n" "$ac_cv_path_GIAC" >&6; }
 then :
   sage_spkg_install_giac=yes
 fi
-       ac_fn_cxx_check_header_compile "$LINENO" "giac/giac.h" "ac_cv_header_giac_giac_h" "$ac_includes_default"
+       ac_fn_cxx_check_header_compile "$LINENO" "giac/giac.h" "ac_cv_header_giac_giac_h" "typedef unsigned char uchar;
+$ac_includes_default"
 if test "x$ac_cv_header_giac_giac_h" = xyes
 then :
 
diff -up src/sage/libs/giac/giac.pxd.orig src/sage/libs/giac/giac.pxd
--- src/sage/libs/giac/giac.pxd.orig	2022-09-19 16:38:18.000000000 -0600
+++ src/sage/libs/giac/giac.pxd	2023-01-15 19:55:21.830822142 -0700
@@ -12,6 +12,11 @@
 from sage.libs.gmp.mpz cimport mpz_t, mpz_set
 from libcpp.string cimport string
 
+cdef extern from *:
+    """
+    typedef unsigned char uchar;
+    """
+
 cdef extern from "giac/giac.h" namespace "giac":
     cdef cppclass context:
          context()
diff -up src/sage/libs/giac/misc.h.orig src/sage/libs/giac/misc.h
--- src/sage/libs/giac/misc.h.orig	2022-09-19 16:38:18.000000000 -0600
+++ src/sage/libs/giac/misc.h	2023-01-15 19:55:21.830822142 -0700
@@ -1,5 +1,6 @@
 #ifndef GIACPYMISC_H
 #define GIACPYMISC_H
+typedef unsigned char uchar;
 #include <giac/giac.h>
 
 #include <fstream>
diff -up src/sage/symbolic/ginac/mpoly-giac.cpp.orig src/sage/symbolic/ginac/mpoly-giac.cpp
--- src/sage/symbolic/ginac/mpoly-giac.cpp.orig	2022-09-19 16:38:19.000000000 -0600
+++ src/sage/symbolic/ginac/mpoly-giac.cpp	2023-01-15 19:55:21.831822125 -0700
@@ -44,6 +44,7 @@
 #include "function.h"
 #include "utils.h"
 
+typedef unsigned char uchar;
 #include <giac/global.h>
 #include <giac/gausspol.h>
 
diff -up src/sage/symbolic/ginac/numeric.cpp.orig src/sage/symbolic/ginac/numeric.cpp
--- src/sage/symbolic/ginac/numeric.cpp.orig	2023-01-15 19:52:42.820659135 -0700
+++ src/sage/symbolic/ginac/numeric.cpp	2023-01-15 19:55:21.831822125 -0700
@@ -77,6 +77,7 @@
 #undef _POSIX_C_SOURCE
 #undef _XOPEN_SOURCE
 
+typedef unsigned char uchar;
 #include <giac/global.h>
 #include <giac/gausspol.h>
 #include <giac/fraction.h>