diff --git a/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-neg-bigint/serialiseData-neg-bigint.uplc b/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-neg-bigint/serialiseData-neg-bigint.uplc
new file mode 100644
index 00000000..c92a913f
--- /dev/null
+++ b/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-neg-bigint/serialiseData-neg-bigint.uplc
@@ -0,0 +1 @@
+(program 0.0.0 [(builtin serialiseData) (con data (I -28446744073709551618))])
\ No newline at end of file
diff --git a/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-neg-bigint/serialiseData-neg-bigint.uplc.expected b/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-neg-bigint/serialiseData-neg-bigint.uplc.expected
new file mode 100644
index 00000000..12dd79be
--- /dev/null
+++ b/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-neg-bigint/serialiseData-neg-bigint.uplc.expected
@@ -0,0 +1 @@
+(program 0.0.0 (con bytestring #c349018ac7230489e80001))
\ No newline at end of file
diff --git a/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-pos-bigint/serialiseData-pos-bigint.uplc b/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-pos-bigint/serialiseData-pos-bigint.uplc
new file mode 100644
index 00000000..193c48a9
--- /dev/null
+++ b/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-pos-bigint/serialiseData-pos-bigint.uplc
@@ -0,0 +1 @@
+(program 0.0.0 [(builtin serialiseData) (con data (I 28446744073709551618))])
\ No newline at end of file
diff --git a/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-pos-bigint/serialiseData-pos-bigint.uplc.expected b/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-pos-bigint/serialiseData-pos-bigint.uplc.expected
new file mode 100644
index 00000000..edb77b86
--- /dev/null
+++ b/crates/uplc/test_data/conformance/evaluation/builtin/semantics/serialiseData/serialiseData-pos-bigint/serialiseData-pos-bigint.uplc.expected
@@ -0,0 +1 @@
+(program 0.0.0 (con bytestring #c249018ac7230489e80002))
\ No newline at end of file