diff --git a/.github/workflows/buildwheel.yml b/.github/workflows/buildwheel.yml
index 565304cd..436f879f 100644
--- a/.github/workflows/buildwheel.yml
+++ b/.github/workflows/buildwheel.yml
@@ -19,7 +19,7 @@ jobs:
         with:
           python-version: '3.13'
 
-      - uses: msys2/setup-msys2@v2.27.0
+      - uses: msys2/setup-msys2@v2.28.0
         with:
           msystem: mingw64
           # path-type inherit is used so that when cibuildwheel calls msys2 to
diff --git a/bin/build_dependencies_unix.sh b/bin/build_dependencies_unix.sh
index ed1156c7..eb0dae5c 100755
--- a/bin/build_dependencies_unix.sh
+++ b/bin/build_dependencies_unix.sh
@@ -42,6 +42,7 @@ do
       echo "  --gmp gmp         - build based on GMP (default)"
       echo "  --gmp mpir        - build based on MPIR (no longer works)"
       echo "  --patch-gmp-arm64 - apply patch to GMP 6.2.1 for OSX arm64"
+      echo "  --patch-C23       - apply patch to GMP 6.3.0 for C23 compatibility"
       echo "  --arb             - build Arb (only needed for flint < 3.0.0)"
       echo
       exit
@@ -88,6 +89,11 @@ do
       PATCH_GMP_ARM64=yes
       shift
     ;;
+    --patch-C23)
+      # Patch GMP 6.3.0 for newer gcc versions
+      PATCH_GMP_C23=yes
+      shift
+    ;;
     --use-gmp-github-mirror)
       USE_GMP_GITHUB_MIRROR=yes
       shift
@@ -164,6 +170,20 @@ if [ $USE_GMP = "gmp" ]; then
         echo --------------------------------------------
         patch -N -Z -p0 < ../../../bin/patch-arm64.diff
       fi
+      #
+      # https://github.com/msys2/MSYS2-packages/issues/5499
+      #
+      # This patch needed for GMP 6.3.0 building with msys2 or probably just
+      # newer gcc versions.
+      #
+      if [ $PATCH_GMP_C23 = "yes" ]; then
+        echo
+        echo --------------------------------------------
+        echo "           patching GMP"
+        echo --------------------------------------------
+        patch -N -Z < ../../../bin/patch-C23.diff
+        autoreconf -fi
+      fi
 
       # Show the output of configfsf.guess
       chmod +x configfsf.guess
diff --git a/bin/cibw_before_all_windows.sh b/bin/cibw_before_all_windows.sh
index c86dc634..1f0b0dae 100755
--- a/bin/cibw_before_all_windows.sh
+++ b/bin/cibw_before_all_windows.sh
@@ -31,4 +31,7 @@ pacman -S --noconfirm \
     #
 
 # This is slow with MinGW:
-bin/build_dependencies_unix.sh --use-gmp-github-mirror
+bin/build_dependencies_unix.sh \
+    --use-gmp-github-mirror\
+    --patch-C23\
+    #
diff --git a/bin/patch-C23.diff b/bin/patch-C23.diff
new file mode 100644
index 00000000..5f1c0214
--- /dev/null
+++ b/bin/patch-C23.diff
@@ -0,0 +1,21 @@
+# HG changeset patch
+# User Marc Glisse <marc.glisse@inria.fr>
+# Date 1738186682 -3600
+# Node ID 8e7bb4ae7a18b1405ea7f9cbcda450b7d920a901
+# Parent  e84c5c785bbe8ed8c3620194e50b65adfc2f5d83
+Complete function prototype in acinclude.m4 for C23 compatibility
+
+diff -r e84c5c785bbe -r 8e7bb4ae7a18 acinclude.m4
+--- a/acinclude.m4	Wed Dec 04 18:26:27 2024 +0100
++++ b/acinclude.m4	Wed Jan 29 22:38:02 2025 +0100
+@@ -609,7 +609,7 @@
+ 
+ #if defined (__GNUC__) && ! defined (__cplusplus)
+ typedef unsigned long long t1;typedef t1*t2;
+-void g(){}
++void g(int,t1 const*,t1,t2,t1 const*,int){}
+ void h(){}
+ static __inline__ t1 e(t2 rp,t2 up,int n,t1 v0)
+ {t1 c,x,r;int i;if(v0){c=1;for(i=1;i<n;i++){x=up[i];r=x+1;rp[i]=r;}}return c;}
+
+
diff --git a/src/flint/types/arb.pyx b/src/flint/types/arb.pyx
index afd80309..74aea43a 100644
--- a/src/flint/types/arb.pyx
+++ b/src/flint/types/arb.pyx
@@ -172,7 +172,7 @@ cdef class arb(flint_scalar):
         [0.333333333333333 +/- 3.71e-16]
         >>> print(arb("3.0"))
         3.00000000000000
-        >>> print(arb("0.1"))  # doctest: +SKIP
+        >>> print(arb("0.1")) # doctest: +SKIP
         [0.100000000000000 +/- 2.23e-17]
         >>> print(arb("1/10")) # doctest: +SKIP
         [0.100000000000000 +/- 2.23e-17]