diff --git a/pkgs/lad/case-insensitivity.patch b/pkgs/lad/case-insensitivity.patch
new file mode 100644
index 0000000..b1370bf
--- /dev/null
+++ b/pkgs/lad/case-insensitivity.patch
@@ -0,0 +1,26 @@
+diff --git a/5.1/assembler.lua b/5.1/assembler.lua
+index fb89b18df2..e5f0b2753b 100644
+--- a/5.1/assembler.lua
++++ b/5.1/assembler.lua
+@@ -100,7 +100,7 @@
+   label <- <name> ":"
+   string <- '"' ('\\' / '\"' / !'"' .)* '"'
+   instruction <- ( <s> ( {<label>} / <number>)? <s> <ln>? <s> {<op>} ( <s> {<param>} )+ <s> ( %nl )+ ) -> {}
+-  op <- [A-Z]+
++  op <- [A-Za-z]+
+   param <- <register> / <number> / <name> / <string>
+   register <- ( "R[" <number> "]" )
+   s <- ( !%nl %s )*
+@@ -310,10 +310,10 @@
+   local b = 3
+   local c = 4
+   if check_label(table[1]) == nil then
+-    op = table[1]
++    op = string.upper (table[1])
+   else
+     set_label(table[1], parsed, n)
+-    op = table[2]
++    op = string.upper (table[2])
+     a = 3
+     b = 4
+     c = 5
diff --git a/pkgs/lad/default.nix b/pkgs/lad/default.nix
index 690cfa9..4c7129f 100644
--- a/pkgs/lad/default.nix
+++ b/pkgs/lad/default.nix
@@ -6,6 +6,7 @@
 , lib
 , wantLad5_1 ? true
 , wantLad5_2 ? true
+, wantCaseInsensitivity ? false
 }:
 
 let
@@ -29,6 +30,7 @@ in stdenv.mkDerivation {
   };
   LUA51 = lib.getExe our-lua51;
   LUA52 = lib.getExe our-lua52;
+  patches = lib.optional wantCaseInsensitivity ./case-insensitivity.patch;
   installPhase = ''
     mkdir -p $out/bin $out/opt/{5.1,5.2}
     cp 5.1/*.lua $out/opt/5.1/