diff --git a/pkgs/tools/system/efibootmgr/arbitrary-filenames.patch b/pkgs/tools/system/efibootmgr/arbitrary-filenames.patch
new file mode 100644
index 00000000000..ae542ac8795
--- /dev/null
+++ b/pkgs/tools/system/efibootmgr/arbitrary-filenames.patch
@@ -0,0 +1,24 @@
+diff -Naur efibootmgr-0.5.4-orig/src/lib/efi.c efibootmgr-0.5.4/src/lib/efi.c
+--- efibootmgr-0.5.4-orig/src/lib/efi.c	2008-01-03 15:34:01.000000000 +0100
++++ efibootmgr-0.5.4/src/lib/efi.c	2012-03-13 22:25:51.000000000 +0100
+@@ -495,7 +495,8 @@
+     int rc, edd_version=0;
+     uint8_t mbr_type=0, signature_type=0;
+     uint64_t start=0, size=0;
+-    efi_char16_t os_loader_path[40];
++    efi_char16_t *os_loader_path;
++    size_t os_loader_path_size;
+ 
+     memset(signature, 0, sizeof(signature));
+ 
+@@ -535,7 +536,9 @@
+ 				     signature,
+ 				     mbr_type, signature_type);
+ 
+-    efichar_from_char(os_loader_path, opts.loader, sizeof(os_loader_path));
++    os_loader_path_size = sizeof(efi_char16_t) * (1 + strlen(opts.loader) / sizeof(char));
++    os_loader_path = malloc(os_loader_path_size);
++    efichar_from_char(os_loader_path, opts.loader, os_loader_path_size);
+     p += make_file_path_device_path (p, os_loader_path);
+     p += make_end_device_path       (p);
+ 
diff --git a/pkgs/tools/system/efibootmgr/default.nix b/pkgs/tools/system/efibootmgr/default.nix
index bf4c429808b..618454d87a4 100644
--- a/pkgs/tools/system/efibootmgr/default.nix
+++ b/pkgs/tools/system/efibootmgr/default.nix
@@ -7,13 +7,14 @@ stdenv.mkDerivation {
 
   buildInputs = [ pciutils zlib perl ];
 
+  patches = [ ./arbitrary-filenames.patch ];
   
   src = fetchurl {
     url = "http://linux.dell.com/efibootmgr/permalink/efibootmgr-${version}.tar.gz";
     sha256 = "0wcfgf8x4p4xfh38m9x3njwsxibm9bhnmvpjj94lj9sk9xxa8qmm";
   };
 
-  patchPhase = ''
+  postPatch = ''
     substituteInPlace "./tools/install.pl" \
       --replace "/usr/bin/perl" "${perl}/bin/perl"
   '';