diff --git a/lib.nix b/lib.nix
index 44de581..92901d1 100644
--- a/lib.nix
+++ b/lib.nix
@@ -127,7 +127,9 @@ let
     if isJoin expr && expr.sep == "." then expr
     else if isRaw expr then expr
     else raw (validString expr);
-  set = var: val: join " = " [ (validSetVariable var) val ];
+  set = var: val:
+    if val == null then null
+    else join " = " [ (validSetVariable var) val ];
 
   # Type: validBlockBody :: a -> [b]
   validBlockBody = body:
diff --git a/lib.test.nix b/lib.test.nix
index 8854a59..9b815c6 100644
--- a/lib.test.nix
+++ b/lib.test.nix
@@ -193,6 +193,10 @@ with nix2lua; pkgs.lib.runTests {
     expr = toLua (lset "parser_config.d2" { });
     expected = "local parser_config.d2 = {  }";
   };
+  "test skips a var definition if value is null" = {
+    expr = toLua (set "vim.opt.number" null);
+    expected = null;
+  };
   "test returns all operations" = {
     expr = toLua (spaceBetween [
       (set "a" (eq (mul (add 1 2) (sub 2 1)) 3))