diff --git a/tvix/Cargo.lock b/tvix/Cargo.lock
index 36c9cef50..523264b32 100644
--- a/tvix/Cargo.lock
+++ b/tvix/Cargo.lock
@@ -177,6 +177,21 @@ version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9e1b586273c5702936fe7b7d6896644d8be71e6314cfe09d3167c95f712589e8"
 
+[[package]]
+name = "bit-set"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0700ddab506f33b20a03b13996eccd309a48e5ff77d0d95926aa0210fb4e95f1"
+dependencies = [
+ "bit-vec",
+]
+
+[[package]]
+name = "bit-vec"
+version = "0.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "349f9b6a179ed607305526ca489b34ad0a41aed5f7980fa90eb03160b69598fb"
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -869,6 +884,7 @@ checksum = "c2806b69cd9f4664844027b64465eacb444c67c1db9c778e341adff0c25cdb0d"
 dependencies = [
  "bitmaps",
  "imbl-sized-chunks",
+ "proptest",
  "rand_core 0.6.4",
  "rand_xoshiro",
  "serde",
@@ -1353,15 +1369,17 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1e0d9cc07f18492d879586c92b485def06bc850da3118075cd45d50e9c95b0e5"
 dependencies = [
+ "bit-set",
  "bitflags",
  "byteorder",
  "lazy_static",
  "num-traits",
- "quick-error",
+ "quick-error 2.0.1",
  "rand 0.8.5",
  "rand_chacha",
  "rand_xorshift",
  "regex-syntax",
+ "rusty-fork",
  "tempfile",
 ]
 
@@ -1420,6 +1438,12 @@ dependencies = [
  "prost",
 ]
 
+[[package]]
+name = "quick-error"
+version = "1.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1d01941d82fa2ab50be1e79e6714289dd7cde78eba4c074bc5a4374f650dfe0"
+
 [[package]]
 name = "quick-error"
 version = "2.0.1"
@@ -1662,6 +1686,18 @@ version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "97477e48b4cf8603ad5f7aaf897467cf42ab4218a38ef76fb14c2d6773a6d6a8"
 
+[[package]]
+name = "rusty-fork"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cb3dcc6e454c328bb824492db107ab7c0ae8fcffe4ad210136ef014458c1bc4f"
+dependencies = [
+ "fnv",
+ "quick-error 1.2.3",
+ "tempfile",
+ "wait-timeout",
+]
+
 [[package]]
 name = "rustyline"
 version = "10.0.0"
@@ -2414,6 +2450,15 @@ version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
 
+[[package]]
+name = "wait-timeout"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f200f5b12eb75f8c1ed65abd4b2db8a6e1b138a20de009dacee265a2498f3f6"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "walkdir"
 version = "2.3.2"
diff --git a/tvix/Cargo.nix b/tvix/Cargo.nix
index a27fe822f..ca3165c1a 100644
--- a/tvix/Cargo.nix
+++ b/tvix/Cargo.nix
@@ -649,6 +649,43 @@ rec {
         };
         resolvedDefaultFeatures = [ "default" "std" ];
       };
+      "bit-set" = rec {
+        crateName = "bit-set";
+        version = "0.5.3";
+        edition = "2015";
+        sha256 = "1wcm9vxi00ma4rcxkl3pzzjli6ihrpn9cfdi0c5b4cvga2mxs007";
+        authors = [
+          "Alexis Beingessner <a.beingessner@gmail.com>"
+        ];
+        dependencies = [
+          {
+            name = "bit-vec";
+            packageId = "bit-vec";
+            usesDefaultFeatures = false;
+          }
+        ];
+        features = {
+          "default" = [ "std" ];
+          "std" = [ "bit-vec/std" ];
+        };
+        resolvedDefaultFeatures = [ "default" "std" ];
+      };
+      "bit-vec" = rec {
+        crateName = "bit-vec";
+        version = "0.6.3";
+        edition = "2015";
+        sha256 = "1ywqjnv60cdh1slhz67psnp422md6jdliji6alq0gmly2xm9p7rl";
+        authors = [
+          "Alexis Beingessner <a.beingessner@gmail.com>"
+        ];
+        features = {
+          "default" = [ "std" ];
+          "serde" = [ "dep:serde" ];
+          "serde_no_std" = [ "serde/alloc" ];
+          "serde_std" = [ "std" "serde/std" ];
+        };
+        resolvedDefaultFeatures = [ "std" ];
+      };
       "bitflags" = rec {
         crateName = "bitflags";
         version = "1.3.2";
@@ -2513,6 +2550,11 @@ rec {
             name = "imbl-sized-chunks";
             packageId = "imbl-sized-chunks";
           }
+          {
+            name = "proptest";
+            packageId = "proptest";
+            optional = true;
+          }
           {
             name = "rand_core";
             packageId = "rand_core 0.6.4";
@@ -2534,6 +2576,10 @@ rec {
           }
         ];
         devDependencies = [
+          {
+            name = "proptest";
+            packageId = "proptest";
+          }
           {
             name = "serde";
             packageId = "serde";
@@ -2547,7 +2593,7 @@ rec {
           "refpool" = [ "dep:refpool" ];
           "serde" = [ "dep:serde" ];
         };
-        resolvedDefaultFeatures = [ "serde" ];
+        resolvedDefaultFeatures = [ "proptest" "serde" ];
       };
       "imbl-sized-chunks" = rec {
         crateName = "imbl-sized-chunks";
@@ -3789,6 +3835,11 @@ rec {
           "Jason Lingle"
         ];
         dependencies = [
+          {
+            name = "bit-set";
+            packageId = "bit-set";
+            optional = true;
+          }
           {
             name = "bitflags";
             packageId = "bitflags";
@@ -3810,7 +3861,7 @@ rec {
           }
           {
             name = "quick-error";
-            packageId = "quick-error";
+            packageId = "quick-error 2.0.1";
             optional = true;
           }
           {
@@ -3833,6 +3884,12 @@ rec {
             packageId = "regex-syntax";
             optional = true;
           }
+          {
+            name = "rusty-fork";
+            packageId = "rusty-fork";
+            optional = true;
+            usesDefaultFeatures = false;
+          }
           {
             name = "tempfile";
             packageId = "tempfile";
@@ -3854,7 +3911,7 @@ rec {
           "timeout" = [ "fork" "rusty-fork/timeout" ];
           "x86" = [ "dep:x86" ];
         };
-        resolvedDefaultFeatures = [ "alloc" "break-dead-code" "lazy_static" "quick-error" "regex-syntax" "std" "tempfile" ];
+        resolvedDefaultFeatures = [ "alloc" "bit-set" "break-dead-code" "default" "fork" "lazy_static" "quick-error" "regex-syntax" "rusty-fork" "std" "tempfile" "timeout" ];
       };
       "prost" = rec {
         crateName = "prost";
@@ -4038,7 +4095,18 @@ rec {
         };
         resolvedDefaultFeatures = [ "default" "std" ];
       };
-      "quick-error" = rec {
+      "quick-error 1.2.3" = rec {
+        crateName = "quick-error";
+        version = "1.2.3";
+        edition = "2015";
+        sha256 = "1q6za3v78hsspisc197bg3g7rpc989qycy8ypr8ap8igv10ikl51";
+        authors = [
+          "Paul Colomiets <paul@colomiets.name>"
+          "Colin Kiegel <kiegel@gmx.de>"
+        ];
+
+      };
+      "quick-error 2.0.1" = rec {
         crateName = "quick-error";
         version = "2.0.1";
         edition = "2018";
@@ -4738,6 +4806,40 @@ rec {
         ];
 
       };
+      "rusty-fork" = rec {
+        crateName = "rusty-fork";
+        version = "0.3.0";
+        edition = "2018";
+        sha256 = "0kxwq5c480gg6q0j3bg4zzyfh2kwmc3v2ba94jw8ncjc8mpcqgfb";
+        authors = [
+          "Jason Lingle"
+        ];
+        dependencies = [
+          {
+            name = "fnv";
+            packageId = "fnv";
+          }
+          {
+            name = "quick-error";
+            packageId = "quick-error 1.2.3";
+          }
+          {
+            name = "tempfile";
+            packageId = "tempfile";
+          }
+          {
+            name = "wait-timeout";
+            packageId = "wait-timeout";
+            optional = true;
+          }
+        ];
+        features = {
+          "default" = [ "timeout" ];
+          "timeout" = [ "wait-timeout" ];
+          "wait-timeout" = [ "dep:wait-timeout" ];
+        };
+        resolvedDefaultFeatures = [ "timeout" "wait-timeout" ];
+      };
       "rustyline" = rec {
         crateName = "rustyline";
         version = "10.0.0";
@@ -6927,7 +7029,7 @@ rec {
           }
         ];
         features = {
-          "arbitrary" = [ "proptest" "test-strategy" ];
+          "arbitrary" = [ "proptest" "test-strategy" "imbl/proptest" ];
           "backtrace-on-stack-overflow" = [ "dep:backtrace-on-stack-overflow" ];
           "backtrace_overflow" = [ "backtrace-on-stack-overflow" ];
           "default" = [ "impure" "arbitrary" "nix_tests" "backtrace_overflow" ];
@@ -7215,6 +7317,24 @@ rec {
           "Sergio Benitez <sb@sergio.bz>"
         ];
 
+      };
+      "wait-timeout" = rec {
+        crateName = "wait-timeout";
+        version = "0.2.0";
+        edition = "2015";
+        crateBin = [ ];
+        sha256 = "1xpkk0j5l9pfmjfh1pi0i89invlavfrd9av5xp0zhxgb29dhy84z";
+        authors = [
+          "Alex Crichton <alex@alexcrichton.com>"
+        ];
+        dependencies = [
+          {
+            name = "libc";
+            packageId = "libc";
+            target = { target, features }: (target."unix" or false);
+          }
+        ];
+
       };
       "walkdir" = rec {
         crateName = "walkdir";
diff --git a/tvix/eval/Cargo.toml b/tvix/eval/Cargo.toml
index 697411029..24e6d33d0 100644
--- a/tvix/eval/Cargo.toml
+++ b/tvix/eval/Cargo.toml
@@ -50,7 +50,7 @@ nix_tests = []
 impure = []
 
 # Enables Arbitrary impls for internal types (required to run tests)
-arbitrary = [ "proptest", "test-strategy" ]
+arbitrary = [ "proptest", "test-strategy", "imbl/proptest" ]
 
 # For debugging use only; not appropriate for production use.
 backtrace_overflow = [ "backtrace-on-stack-overflow" ]
diff --git a/tvix/eval/src/value/arbitrary.rs b/tvix/eval/src/value/arbitrary.rs
index cd7629cfb..f0bdc06fd 100644
--- a/tvix/eval/src/value/arbitrary.rs
+++ b/tvix/eval/src/value/arbitrary.rs
@@ -1,9 +1,10 @@
 //! Support for configurable generation of arbitrary nix values
 
+use imbl::proptest::{ord_map, vector};
 use proptest::{prelude::*, strategy::BoxedStrategy};
 use std::ffi::OsString;
 
-use super::{NixAttrs, NixList, NixString, Value};
+use super::{attrs::AttrsRep, NixAttrs, NixList, NixString, Value};
 
 #[derive(Clone)]
 pub enum Parameters {
@@ -25,6 +26,39 @@ impl Default for Parameters {
     }
 }
 
+impl Arbitrary for NixAttrs {
+    type Parameters = Parameters; // <BTreeMap<NixString, Value> as Arbitrary>::Parameters;
+    type Strategy = BoxedStrategy<Self>;
+
+    fn arbitrary_with(args: Self::Parameters) -> Self::Strategy {
+        prop_oneof![
+            // Empty attrs representation
+            Just(Self(AttrsRep::Empty)),
+            // KV representation (name/value pairs)
+            (
+                any_with::<Value>(args.clone()),
+                any_with::<Value>(args.clone())
+            )
+                .prop_map(|(name, value)| Self(AttrsRep::KV { name, value })),
+            // Map representation
+            ord_map(NixString::arbitrary(), Value::arbitrary_with(args), 0..100)
+                .prop_map(|map| Self(AttrsRep::Im(map)))
+        ]
+        .boxed()
+    }
+}
+
+impl Arbitrary for NixList {
+    type Parameters = <Value as Arbitrary>::Parameters;
+    type Strategy = BoxedStrategy<Self>;
+
+    fn arbitrary_with(args: Self::Parameters) -> Self::Strategy {
+        vector(<Value as Arbitrary>::arbitrary_with(args), 0..100)
+            .prop_map(NixList::from)
+            .boxed()
+    }
+}
+
 impl Arbitrary for Value {
     type Parameters = Parameters;
     type Strategy = BoxedStrategy<Self>;
@@ -65,14 +99,8 @@ fn leaf_value() -> impl Strategy<Value = Value> {
 fn non_internal_value() -> impl Strategy<Value = Value> {
     leaf_value().prop_recursive(3, 5, 5, |inner| {
         prop_oneof![
-            any_with::<NixAttrs>((
-                Default::default(),
-                Default::default(),
-                Parameters::Strategy(inner.clone())
-            ))
-            .prop_map(Value::attrs),
-            any_with::<NixList>((Default::default(), Parameters::Strategy(inner)))
-                .prop_map(Value::List)
+            NixAttrs::arbitrary_with(Parameters::Strategy(inner.clone())).prop_map(Value::attrs),
+            any_with::<NixList>(Parameters::Strategy(inner)).prop_map(Value::List)
         ]
     })
 }
diff --git a/tvix/eval/src/value/attrs.rs b/tvix/eval/src/value/attrs.rs
index 6515fb515..10d071720 100644
--- a/tvix/eval/src/value/attrs.rs
+++ b/tvix/eval/src/value/attrs.rs
@@ -24,7 +24,7 @@ use super::Value;
 mod tests;
 
 #[derive(Clone, Debug, Deserialize)]
-enum AttrsRep {
+pub(super) enum AttrsRep {
     Empty,
 
     Im(OrdMap<NixString, Value>),
@@ -92,7 +92,7 @@ impl AttrsRep {
 
 #[repr(transparent)]
 #[derive(Clone, Debug, Default)]
-pub struct NixAttrs(AttrsRep);
+pub struct NixAttrs(pub(super) AttrsRep);
 
 impl<K, V> FromIterator<(K, V)> for NixAttrs
 where
@@ -192,36 +192,6 @@ impl<'de> Deserialize<'de> for NixAttrs {
     }
 }
 
-#[cfg(feature = "arbitrary")]
-mod arbitrary {
-    use super::*;
-    use std::collections::BTreeMap;
-
-    use proptest::prelude::*;
-    use proptest::prop_oneof;
-    use proptest::strategy::{BoxedStrategy, Just, Strategy};
-
-    impl Arbitrary for NixAttrs {
-        type Parameters = <BTreeMap<NixString, Value> as Arbitrary>::Parameters;
-
-        type Strategy = BoxedStrategy<Self>;
-
-        fn arbitrary_with(args: Self::Parameters) -> Self::Strategy {
-            prop_oneof![
-                Just(Self(AttrsRep::Empty)),
-                (
-                    any_with::<Value>(args.2.clone()),
-                    any_with::<Value>(args.2.clone())
-                )
-                    .prop_map(|(name, value)| Self(AttrsRep::KV { name, value })),
-                any_with::<BTreeMap<NixString, Value>>(args)
-                    .prop_map(|map| Self::from_iter(map.into_iter()))
-            ]
-            .boxed()
-        }
-    }
-}
-
 impl NixAttrs {
     pub fn empty() -> Self {
         Self(AttrsRep::Empty)
diff --git a/tvix/eval/src/value/list.rs b/tvix/eval/src/value/list.rs
index 6d830b728..5d1daf7c9 100644
--- a/tvix/eval/src/value/list.rs
+++ b/tvix/eval/src/value/list.rs
@@ -35,29 +35,6 @@ impl From<Vector<Value>> for NixList {
     }
 }
 
-#[cfg(feature = "arbitrary")]
-mod arbitrary {
-    use proptest::{
-        prelude::{any_with, Arbitrary},
-        strategy::{BoxedStrategy, Strategy},
-    };
-
-    use super::*;
-
-    impl Arbitrary for NixList {
-        // TODO(tazjin): im seems to implement arbitrary instances,
-        // but I couldn't figure out how to enable them.
-        type Parameters = <Vec<Value> as Arbitrary>::Parameters;
-        type Strategy = BoxedStrategy<Self>;
-
-        fn arbitrary_with(args: Self::Parameters) -> Self::Strategy {
-            any_with::<Vec<Value>>(args)
-                .prop_map(NixList::from_vec)
-                .boxed()
-        }
-    }
-}
-
 impl NixList {
     pub fn len(&self) -> usize {
         self.0.len()
diff --git a/tvix/eval/src/value/mod.rs b/tvix/eval/src/value/mod.rs
index af8627bf9..9ab23043c 100644
--- a/tvix/eval/src/value/mod.rs
+++ b/tvix/eval/src/value/mod.rs
@@ -556,12 +556,6 @@ impl From<PathBuf> for Value {
     }
 }
 
-impl From<Vec<Value>> for Value {
-    fn from(val: Vec<Value>) -> Self {
-        Self::List(NixList::from_vec(val))
-    }
-}
-
 fn type_error(expected: &'static str, actual: &Value) -> ErrorKind {
     ErrorKind::TypeError {
         expected,