diff --git a/ocaml-curses-configure-c99.patch b/ocaml-curses-configure-c99.patch
new file mode 100644
index 0000000..a09c1bd
--- /dev/null
+++ b/ocaml-curses-configure-c99.patch
@@ -0,0 +1,20 @@
+Define NCURSES_WIDECHAR, so that <ncursesw/curses.h> actually declares
+the probed addnwstr function.  This follows Thomas Dickey's suggestion
+on the bug-ncurses list:
+
+  <https://lists.nongnu.org/archive/html/bug-ncurses/2023-03/msg00003.html>
+
+Submitted upstream: <https://savannah.nongnu.org/bugs/index.php?64109>
+
+diff --git a/configure.ac b/configure.ac
+index 15ca4087b5d9ee2b..24d5fa48960a5601 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -126,6 +126,7 @@ then
+     AC_MSG_CHECKING(for wide character support in ncurses library)
+     AC_TRY_LINK(
+       [#include <wchar.h>
++       #define NCURSES_WIDECHAR 1
+        #include CURSES_HEADER
+       ],
+       [wchar_t wch = 0;
diff --git a/ocaml-curses.spec b/ocaml-curses.spec
index cf21825..c33807a 100644
--- a/ocaml-curses.spec
+++ b/ocaml-curses.spec
@@ -3,12 +3,13 @@
 
 Name:           ocaml-curses
 Version:        1.0.4
-Release:        29%{?dist}
+Release:        30%{?dist}
 Summary:        OCaml bindings for ncurses
 License:        LGPLv2+
 
 URL:            http://savannah.nongnu.org/projects/ocaml-tmk/
 Source0:        http://download.savannah.gnu.org/releases/ocaml-tmk/%{name}-%{version}.tar.gz
+Patch0: ocaml-curses-configure-c99.patch
 
 BuildRequires: make
 BuildRequires:  ocaml >= 4.00.1
@@ -41,7 +42,7 @@ developing applications that use %{name}.
 
 
 %prep
-%setup -q
+%autosetup -p1
 
 autoreconf
 
@@ -89,6 +90,9 @@ ocamlfind install curses META *.cmi *.cma *.a *.so *.mli
 
 
 %changelog
+* Tue Apr 25 2023 Florian Weimer <fweimer@redhat.com> - 1.0.4-30
+- Port configure script to C99
+
 * Tue Jan 24 2023 Richard W.M. Jones <rjones@redhat.com> - 1.0.4-29
 - Rebuild OCaml packages for F38