diff --git a/racket-configure-c99.patch b/racket-configure-c99.patch
new file mode 100644
index 0000000..f4f4014
--- /dev/null
+++ b/racket-configure-c99.patch
@@ -0,0 +1,29 @@
+Fix generic C99 compatibility issue in the configure script because it
+was generated by a historic autoconf version.  This will go away once
+upstream re-runs autoconf, and until then, the patch will keep
+applying, so there is no need to upstream it.
+
+diff --git a/src/lt/configure b/src/lt/configure
+index e3f5aa6ed9a21307..aa4f50637331d427 100755
+--- a/src/lt/configure
++++ b/src/lt/configure
+@@ -2465,7 +2465,7 @@ if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+   echo "$as_me:$LINENO: \$? = $ac_status" >&5
+   (exit $ac_status); }; }; then
+   for ac_declaration in \
+-   '' \
++   '#include <stdlib.h>' \
+    'extern "C" void std::exit (int) throw (); using std::exit;' \
+    'extern "C" void std::exit (int); using std::exit;' \
+    'extern "C" void exit (int) throw ();' \
+@@ -3640,8 +3640,8 @@ main ()
+   for (i = 0; i < 256; i++)
+     if (XOR (islower (i), ISLOWER (i))
+ 	|| toupper (i) != TOUPPER (i))
+-      exit(2);
+-  exit (0);
++      return 2;
++  return 0;
+ }
+ _ACEOF
+ rm -f conftest$ac_exeext
diff --git a/racket.spec b/racket.spec
index 16914bf..10e7203 100644
--- a/racket.spec
+++ b/racket.spec
@@ -1,6 +1,6 @@
 Name:           racket
 Version:        7.4
-Release:        9%{?dist}
+Release:        10%{?dist}
 Summary:        General purpose programming language
 
 License:        GPLv3 and LGPLv3 and MIT
@@ -16,6 +16,7 @@ Source0:        https://mirror.racket-lang.org/installers/%{version}/%{name}-%{v
 # Note: SRFI 5 was replaced with a FOSS implementation.  Only
 #       nonfree docs need to be removed by this patch now.
 Patch0:         racket-7.4-remove-nonfree.patch
+Patch1: racket-configure-c99.patch
 
 # Issue Building for armv7hl in koji
 ExcludeArch: %{arm} s390x
@@ -249,6 +250,9 @@ A local installation of the Racket documentation system.
 %{_datadir}/doc/racket
 
 %changelog
+* Wed Apr 26 2023 Florian Weimer <fweimer@redhat.com> - 7.4-10
+- Port configure script to C99
+
 * Fri Jan 20 2023 Fedora Release Engineering <releng@fedoraproject.org> - 7.4-9
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_38_Mass_Rebuild