diff --git a/simplicity-sys/src/tests/ffi.rs b/simplicity-sys/src/tests/ffi.rs
index 25cc1be5..410925b0 100644
--- a/simplicity-sys/src/tests/ffi.rs
+++ b/simplicity-sys/src/tests/ffi.rs
@@ -398,6 +398,7 @@ pub mod eval {
             dag: *const CDagNode,
             type_dag: *mut CType,
             len: c_size_t,
+            min_cost: ubounded,
             budget: *const ubounded,
             env: *const elements::CTxEnv,
         ) -> SimplicityErr;
@@ -444,6 +445,7 @@ pub mod eval {
             dag,
             type_dag,
             len,
+            0,
             budget,
             env,
         )
diff --git a/simplicity-sys/src/tests/mod.rs b/simplicity-sys/src/tests/mod.rs
index 83071d86..bf8a9eb2 100644
--- a/simplicity-sys/src/tests/mod.rs
+++ b/simplicity-sys/src/tests/mod.rs
@@ -317,7 +317,7 @@ pub fn run_program(
         }
 
         // 9. Run the program
-        let budget_ptr = budget.map(|b| b as *const _).unwrap_or(ptr::null());
+        let budget_ptr = budget.as_ref().map(|b| b as *const _).unwrap_or(ptr::null());
         let env_ptr = env.map(|e| e as *const _).unwrap_or(ptr::null());
         result.eval_result = simplicity_evalTCOProgram(dag, type_dag, len, budget_ptr, env_ptr);
     }