diff --git a/pkgs/os-specific/linux/syslinux/default.nix b/pkgs/os-specific/linux/syslinux/default.nix
index 3c01516b0815..93e5d591a9d9 100644
--- a/pkgs/os-specific/linux/syslinux/default.nix
+++ b/pkgs/os-specific/linux/syslinux/default.nix
@@ -8,8 +8,7 @@ stdenv.mkDerivation rec {
     sha256 = "03l5iifwlg1wyb4yh98i0b7pd4j55a1c9y74q1frs47a5dnrilr6";
   };
 
-  # gcc5-fix should be in 6.04+, so remove if it fails to apply.
-  patches = [ ./perl-deps.patch ./gcc5-fix.patch ];
+  patches = [ ./perl-deps.patch ];
 
   buildInputs = [ nasm perl libuuid ];
 
diff --git a/pkgs/os-specific/linux/syslinux/gcc5-fix.patch b/pkgs/os-specific/linux/syslinux/gcc5-fix.patch
deleted file mode 100644
index dc44b1880583..000000000000
--- a/pkgs/os-specific/linux/syslinux/gcc5-fix.patch
+++ /dev/null
@@ -1,26 +0,0 @@
-diff --git a/com32/include/menu.h b/com32/include/menu.h
-index bc0182f..b0251e4 100644
---- a/com32/include/menu.h
-+++ b/com32/include/menu.h
-@@ -195,7 +195,7 @@ void local_cursor_enable(bool);
- 
- static inline int my_isspace(char c)
- {
--    return (unsigned char)c <= ' ';
-+    return (unsigned char)c <= ' ' || (unsigned char)c == '\x7f';
- }
- 
- int my_isxdigit(char c);
-diff --git a/com32/menu/readconfig.c b/com32/menu/readconfig.c
-index b7814be..a433fad 100644
---- a/com32/menu/readconfig.c
-+++ b/com32/menu/readconfig.c
-@@ -299,7 +299,7 @@ static char *copy_sysappend_string(char *dst, const char *src)
-     char c;
- 
-     while ((c = *src++)) {
--	if (c <= ' ' && c == '\x7f') {
-+	if (my_isspace(c)) {
- 	    if (!was_space)
- 		*dst++ = '_';
- 	    was_space = true;
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 5a96d5c455c5..e924feaf78e9 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -10048,7 +10048,13 @@ let
 
   sysklogd = callPackage ../os-specific/linux/sysklogd { };
 
-  syslinux = callPackage ../os-specific/linux/syslinux { };
+  syslinux = callPackage ../os-specific/linux/syslinux {
+    # Using GCC5 with 6.03 creates a broken isolinux.bin
+    # Make sure to test booting the livecd on a bios system
+    # if changing this override.
+    # nixos.tests.bootBiosCdrom is useful for this.
+    stdenv = overrideCC stdenv gcc48;
+  };
 
   sysstat = callPackage ../os-specific/linux/sysstat { };