diff --git a/Cargo.lock b/Cargo.lock
index 2c0d8f02..22a9b35b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -858,6 +858,7 @@ dependencies = [
  "serde",
  "serde_json",
  "simplicity-lang",
+ "simplicityhl",
 ]
 
 [[package]]
diff --git a/Cargo.toml b/Cargo.toml
index 8f977160..2613afd7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -51,6 +51,10 @@ ariadne = "=0.5.0"
 [target.wasm32-unknown-unknown.dependencies]
 getrandom = { version = "0.2", features = ["js"] }
 
+[dev-dependencies]
+# Tests always build with `serde`, so test code needs no `cfg(feature = "serde")`.
+simplicityhl = { path = ".", default-features = false, features = ["serde"] }
+
 [workspace]
 members = ["codegen", "fuzz", "bitcoind-tests"]
 
diff --git a/src/lib.rs b/src/lib.rs
index 7bc750db..acf2b4fd 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -20,7 +20,7 @@ pub mod source;
 mod template_program;
 pub mod unstable;
 
-#[cfg(all(test, feature = "serde"))]
+#[cfg(test)]
 mod error_cases;
 #[cfg(feature = "serde")]
 mod serde;
@@ -701,7 +701,6 @@ pub(crate) mod tests {
             }
         }
 
-        #[cfg(feature = "serde")]
         pub fn with_argument_file<P: AsRef<Path>>(
             self,
             arguments_file_path: P,
@@ -775,7 +774,6 @@ pub(crate) mod tests {
             .with_arguments(Arguments::default())
         }
 
-        #[cfg(feature = "serde")]
         pub fn with_witness_file<P: AsRef<Path>>(
             self,
             witness_file_path: P,
@@ -808,7 +806,6 @@ pub(crate) mod tests {
             }
         }
 
-        #[cfg(feature = "serde")]
         pub fn get_encoding(self) -> String {
             let program_bytes = self.program.commit().to_vec_without_witness();
             Base64Display::new(&program_bytes, &STANDARD).to_string()
@@ -870,7 +867,6 @@ pub(crate) mod tests {
             }
         }
 
-        #[cfg(feature = "serde")]
         pub fn get_encoding_with_witness(self) -> (String, String) {
             let (program_bytes, witness_bytes) = self.program.redeem().to_vec_with_witness();
             (
@@ -1142,7 +1138,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn sighash_non_interactive_fee_bump() {
         let mut t = TestCase::program_file("./examples/non_interactive_fee_bump.simf")
             .with_witness_file("./examples/non_interactive_fee_bump.wit");
@@ -1153,7 +1148,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn escrow_with_delay_timeout() {
         TestCase::program_file("./examples/escrow_with_delay.simf")
             .with_sequence(1000)
@@ -1170,7 +1164,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn hodl_vault() {
         TestCase::program_file("./examples/hodl_vault.simf")
             .with_lock_time(1000)
@@ -1180,7 +1173,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn htlc_complete() {
         TestCase::program_file("./examples/htlc.simf")
             .print_sighash_all()
@@ -1189,7 +1181,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn kitchen_sink() {
         TestCase::template_file_with_unstable(
             "./examples/kitchen_sink.simf",
@@ -1201,7 +1192,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn last_will_inherit() {
         TestCase::program_file_with_unstable("./examples/last_will.simf", UnstableFeatures::all())
             .with_sequence(25920)
@@ -1320,7 +1310,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn p2ms() {
         TestCase::program_file("./examples/p2ms.simf")
             .print_sighash_all()
@@ -1329,7 +1318,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn p2pk() {
         TestCase::template_file("./examples/p2pk.simf")
             .with_argument_file("./examples/p2pk.args")
@@ -1339,7 +1327,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn p2pkh() {
         TestCase::program_file("./examples/p2pkh.simf")
             .print_sighash_all()
@@ -1348,7 +1335,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn presigned_vault_complete() {
         TestCase::program_file("./examples/presigned_vault.simf")
             .with_sequence(1000)
@@ -1358,7 +1344,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn sighash_all_anyonecanpay() {
         TestCase::program_file("./examples/sighash_all_anyonecanpay.simf")
             .with_witness_file("./examples/sighash_all_anyonecanpay.wit")
@@ -1366,7 +1351,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn sighash_all_anyprevout() {
         TestCase::program_file("./examples/sighash_all_anyprevout.simf")
             .with_witness_file("./examples/sighash_all_anyprevout.wit")
@@ -1374,7 +1358,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn sighash_all_anyprevoutanyscript() {
         TestCase::program_file("./examples/sighash_all_anyprevoutanyscript.simf")
             .with_witness_file("./examples/sighash_all_anyprevoutanyscript.wit")
@@ -1382,7 +1365,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn sighash_none() {
         TestCase::program_file("./examples/sighash_none.simf")
             .with_witness_file("./examples/sighash_none.wit")
@@ -1390,7 +1372,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn sighash_single() {
         TestCase::program_file("./examples/sighash_single.simf")
             .with_witness_file("./examples/sighash_single.wit")
@@ -1398,7 +1379,6 @@ pub(crate) mod tests {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn transfer_with_timeout_transfer() {
         TestCase::program_file("./examples/transfer_with_timeout.simf")
             .print_sighash_all()
@@ -1571,7 +1551,6 @@ fn main() {
             .any(|d| matches!(d.error(), Error::RawHashJetsUnavailable)));
     }
 
-    #[cfg(feature = "serde")]
     mod regression {
         use super::TestCase;
 
@@ -1826,7 +1805,6 @@ fn main() {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn enum_match_witness_file_variant_name() {
         // The witness file names the variant; resolution constructs the
         // enum value at the declared type.
diff --git a/src/witness.rs b/src/witness.rs
index 815524fa..bbe85a61 100644
--- a/src/witness.rs
+++ b/src/witness.rs
@@ -358,9 +358,7 @@ mod tests {
     use super::*;
     use crate::ast::ElementsJetHinter;
     use crate::parse::ParseFromStr;
-    #[cfg(feature = "serde")]
     use crate::str::Identifier;
-    #[cfg(feature = "serde")]
     use crate::types::{EnumInfo, EnumVariantInfo, TypeConstructible};
     use crate::value::ValueConstructible;
     use crate::{ast, parse, CompiledProgram, SatisfiedProgram};
@@ -438,7 +436,6 @@ fn main() {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn unresolved_values_resolve_against_declared_types() {
         let u32_ty = ResolvedType::parse_from_str("u32").unwrap();
         let sig_ty = ResolvedType::parse_from_str("Signature").unwrap();
@@ -494,7 +491,6 @@ fn main() {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn unresolved_values_parse_from_json() {
         // Bare strings and legacy value/type maps may be mixed in one file.
         let s = r#"{
@@ -523,7 +519,6 @@ fn main() {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn enum_witness_resolves_by_variant_name() {
         let variants: Arc<[EnumVariantInfo]> = ["Inherit", "ColdSpend", "HotSpend"]
             .into_iter()
@@ -564,7 +559,6 @@ fn main() {
     }
 
     #[test]
-    #[cfg(feature = "serde")]
     fn enum_witness_resolves_inside_composite_types() {
         let variants: Arc<[EnumVariantInfo]> = ["Hot", "Cold"]
             .into_iter()
diff --git a/tests/cli.rs b/tests/cli.rs
index 486b48ff..a0246cfd 100644
--- a/tests/cli.rs
+++ b/tests/cli.rs
@@ -251,8 +251,7 @@ fn cli_reserved_crate_mapping_fails() {
 
 /// The output carries the version of the compiler that produced it, so the exact
 /// compiler can be identified from a shared artifact (different versions can
-/// produce different CMRs from the same source). JSON output requires `serde`.
-#[cfg(feature = "serde")]
+/// produce different CMRs from the same source).
 #[test]
 fn cli_output_includes_compiler_version() {
     let file = Path::new(env!("CARGO_TARGET_TMPDIR")).join("output_version.simf");