diff --git a/pkgs/development/libraries/gnu-efi/default.nix b/pkgs/development/libraries/gnu-efi/default.nix
index fe078db1206b..31b6f7c7d228 100644
--- a/pkgs/development/libraries/gnu-efi/default.nix
+++ b/pkgs/development/libraries/gnu-efi/default.nix
@@ -1,5 +1,5 @@
 { lib, stdenv, buildPackages, fetchFromGitHub, pciutils
-, gitUpdater }:
+, gitUpdater, fwupd-efi, ipxe, refind, syslinux }:
 
 stdenv.mkDerivation rec {
   pname = "gnu-efi";
@@ -27,9 +27,14 @@ stdenv.mkDerivation rec {
       --replace "-Werror" ""
   '';
 
-  passthru.updateScript = gitUpdater {
-    # No nicer place to find latest release.
-    url = "https://git.code.sf.net/p/gnu-efi/code";
+  passthru = {
+    updateScript = gitUpdater {
+      # No nicer place to find latest release.
+      url = "https://git.code.sf.net/p/gnu-efi/code";
+    };
+    tests = {
+      inherit fwupd-efi ipxe refind syslinux;
+    };
   };
 
   meta = with lib; {
diff --git a/pkgs/os-specific/linux/syslinux/default.nix b/pkgs/os-specific/linux/syslinux/default.nix
index b976a3be83e5..6023c6e82ff8 100644
--- a/pkgs/os-specific/linux/syslinux/default.nix
+++ b/pkgs/os-specific/linux/syslinux/default.nix
@@ -69,6 +69,8 @@ stdenv.mkDerivation {
       "sha256-dVzXBi/oSV9vYgU85mRFHBKuZdup+1x1BipJX74ED7E=")
     # Fixes build with "modern" gnu-efi
     ./import-efisetjmp.patch
+    # Upstream patch: https://www.syslinux.org/archives/2024-February/026903.html
+    ./define-wchar_t.patch
   ];
 
   postPatch = ''
diff --git a/pkgs/os-specific/linux/syslinux/define-wchar_t.patch b/pkgs/os-specific/linux/syslinux/define-wchar_t.patch
new file mode 100644
index 000000000000..92baf101fb41
--- /dev/null
+++ b/pkgs/os-specific/linux/syslinux/define-wchar_t.patch
@@ -0,0 +1,11 @@
+diff --git a/com32/include/stddef.h b/com32/include/stddef.h
+index f52d62f3..437b11f2 100644
+--- a/com32/include/stddef.h
++++ b/com32/include/stddef.h
+@@ -29,4 +29,6 @@
+  */
+ #define container_of(p, c, m) ((c *)((char *)(p) - offsetof(c,m)))
+ 
++typedef short wchar_t;
++
+ #endif /* _STDDEF_H */