diff --git a/gleam.toml b/gleam.toml
index eef183d..85c95f7 100644
--- a/gleam.toml
+++ b/gleam.toml
@@ -22,6 +22,7 @@ parallel_map = ">= 2.0.0 and < 3.0.0"
 filepath = ">= 1.0.0 and < 2.0.0"
 tom = ">= 1.0.0 and < 2.0.0"
 file_streams = ">= 0.6.3 and < 1.0.0"
+decode = ">= 0.2.0 and < 1.0.0"
 
 [dev-dependencies]
 gleeunit = "~> 1.0"
diff --git a/manifest.toml b/manifest.toml
index a29e23e..0e5ff33 100644
--- a/manifest.toml
+++ b/manifest.toml
@@ -3,6 +3,7 @@
 
 packages = [
   { name = "argv", version = "1.0.2", build_tools = ["gleam"], requirements = [], otp_app = "argv", source = "hex", outer_checksum = "BA1FF0929525DEBA1CE67256E5ADF77A7CDDFE729E3E3F57A5BDCAA031DED09D" },
+  { name = "decode", version = "0.2.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "decode", source = "hex", outer_checksum = "965F517F67B8C172CA27A5C8E34C73733139E8C9E64736181B8C3179281F9793" },
   { name = "file_streams", version = "0.6.3", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "file_streams", source = "hex", outer_checksum = "EC0DA36A4A5A79EB1281DD21247F062AD64D171D53C06ED4B4F520B0BC77F710" },
   { name = "filepath", version = "1.0.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "filepath", source = "hex", outer_checksum = "EFB6FF65C98B2A16378ABC3EE2B14124168C0CE5201553DE652E2644DCFDB594" },
   { name = "gleam_community_ansi", version = "1.4.0", build_tools = ["gleam"], requirements = ["gleam_community_colour", "gleam_stdlib"], otp_app = "gleam_community_ansi", source = "hex", outer_checksum = "FE79E08BF97009729259B6357EC058315B6FBB916FAD1C2FF9355115FEB0D3A4" },
@@ -27,7 +28,8 @@ packages = [
 
 [requirements]
 argv = { version = "~> 1.0" }
-file_streams = { version = ">= 0.6.3 and < 1.0.0"}
+decode = { version = ">= 0.2.0 and < 1.0.0"}
+file_streams = { version = ">= 0.6.3 and < 1.0.0" }
 filepath = { version = ">= 1.0.0 and < 2.0.0" }
 gleam_erlang = { version = "~> 0.7" }
 gleam_json = { version = "~> 1.0" }
diff --git a/src/gladvent/internal/cmd/run.gleam b/src/gladvent/internal/cmd/run.gleam
index b36339f..88ed4d0 100644
--- a/src/gladvent/internal/cmd/run.gleam
+++ b/src/gladvent/internal/cmd/run.gleam
@@ -1,3 +1,4 @@
+import decode
 import filepath
 import gladvent/internal/cmd.{Ending, Endless}
 import gladvent/internal/parse.{type Day}
@@ -132,24 +133,38 @@ type GleamErr {
   )
 }
 
-fn decode_gleam_err() {
-  dynamic.decode6(
-    GleamErr,
-    dynamic.field(atom.create_from_string("gleam_error"), atom.from_dynamic),
-    dynamic.field(atom.create_from_string("module"), dynamic.string),
-    dynamic.field(atom.create_from_string("function"), dynamic.string),
-    dynamic.field(atom.create_from_string("line"), dynamic.int),
-    dynamic.field(atom.create_from_string("message"), dynamic.string),
-    dynamic.any([
-      dynamic.field(
-        atom.create_from_string("value"),
-        dynamic.optional(dynamic.dynamic),
-      ),
-      fn(_) { Ok(None) },
-    ]),
+fn decode_gleam_err(dyn: dynamic.Dynamic) {
+  decode.into({
+    use gleam_error <- decode.parameter
+    use module <- decode.parameter
+    use function <- decode.parameter
+    use line <- decode.parameter
+    use message <- decode.parameter
+    use value <- decode.parameter
+    GleamErr(gleam_error, module, function, line, message, value)
+  })
+  |> decode.field(atom.create_from_string("gleam_error"), {
+    use dyn <- decode.then(decode.dynamic)
+    case atom.from_dynamic(dyn) {
+      Ok(a) -> decode.into(a)
+      Error(e) ->
+        decode.fail("failed to decode gleam error: " <> string.inspect(e))
+    }
+  })
+  |> decode.field(atom.create_from_string("module"), decode.string)
+  |> decode.field(atom.create_from_string("function"), decode.string)
+  |> decode.field(atom.create_from_string("line"), decode.int)
+  |> decode.field(atom.create_from_string("message"), decode.string)
+  |> decode.field(
+    atom.create_from_string("value"),
+    decode.optional(decode.dynamic),
   )
+  |> decode.from(dyn)
+  |> io.debug
 }
 
+import gleam/io
+
 fn gleam_err_to_string(g: GleamErr) -> String {
   string.join(
     [