diff --git a/src/test_suite/multiprocessing_utils.py b/src/test_suite/multiprocessing_utils.py
index 96cfed3..e462726 100644
--- a/src/test_suite/multiprocessing_utils.py
+++ b/src/test_suite/multiprocessing_utils.py
@@ -14,7 +14,7 @@
 
 
 def process_target(
-    harness_ctx: HarnessCtx, library: ctypes.CDLL, serialized_instruction_context: str
+    harness_ctx: HarnessCtx, library: ctypes.CDLL, context: ContextType
 ) -> invoke_pb.InstrEffects | None:
     """
     Process an instruction through a provided shared library and return the result.
@@ -26,6 +26,11 @@ def process_target(
     Returns:
         - invoke_pb.InstrEffects | None: Result of instruction execution.
     """
+
+    serialized_instruction_context = context.SerializeToString(deterministic=True)
+    if serialized_instruction_context is None:
+        return None
+
     # Prepare input data and output buffers
     in_data = serialized_instruction_context
     in_ptr = (ctypes.c_uint8 * len(in_data))(*in_data)
@@ -143,25 +148,6 @@ def read_context(harness_ctx: HarnessCtx, test_file: Path) -> message.Message |
     return context
 
 
-def read_fixture_serialized(fixture_file: Path) -> str | None:
-    """
-    Same as read_instr, but for InstrFixture protobuf messages.
-
-    DOES NOT SUPPORT HUMAN READABLE MESSAGES!!!
-
-    Args:
-        - fixture_file (Path): Path to the instruction fixture message.
-
-    Returns:
-        - str | None: Serialized instruction fixture, or None if reading failed.
-    """
-    fixture = read_fixture(fixture_file)
-    if fixture is None:
-        return None
-    # Serialize instruction fixture to string (pickleable)
-    return fixture.SerializeToString(deterministic=True)
-
-
 def read_fixture(fixture_file: Path) -> message.Message | None:
     """
     Reads in test files and generates an Fixture Protobuf object for a test case.
@@ -209,10 +195,12 @@ def decode_single_test_case(test_file: Path) -> int:
     if test_file.suffix == ".fix":
         fn_entrypoint = extract_metadata(test_file).fn_entrypoint
         harness_ctx = ENTRYPOINT_HARNESS_MAP[fn_entrypoint]
-        serialized_protobuf = read_fixture_serialized(test_file)
+        fixture = read_fixture(test_file)
+        serialized_protobuf = fixture.SerializeToString(deterministic=True)
     else:
         harness_ctx = globals.default_harness_ctx
-        serialized_protobuf = read_context_serialized(harness_ctx, test_file)
+        context = read_context(harness_ctx, test_file)
+        serialized_protobuf = context.SerializeToString(deterministic=True)
 
     # Skip if input is invalid
     if serialized_protobuf is None:
@@ -378,18 +366,6 @@ def initialize_process_output_buffers(randomize_output_buffer=False):
         )
 
 
-def serialize_context(harness_ctx: HarnessCtx, file: Path) -> str | None:
-    if file.suffix == ".fix":
-        fixture = harness_ctx.fixture_type()
-        fixture.ParseFromString(file.open("rb").read())
-        serialized_instr_context = fixture.input.SerializeToString(deterministic=True)
-    else:
-        serialized_instr_context = read_context_serialized(harness_ctx, file)
-
-    assert serialized_instr_context is not None, f"Unable to read {file.name}"
-    return serialized_instr_context
-
-
 def run_test(test_file: Path) -> tuple[str, int, dict | None]:
     """
     Runs a single test from start to finish.
diff --git a/src/test_suite/test_suite.py b/src/test_suite/test_suite.py
index 856835b..0cb3722 100644
--- a/src/test_suite/test_suite.py
+++ b/src/test_suite/test_suite.py
@@ -22,7 +22,6 @@
     process_target,
     run_test,
     read_context,
-    serialize_context,
 )
 import test_suite.globals as globals
 from test_suite.util import set_ld_preload_asan
@@ -98,13 +97,14 @@ def execute(
         if file.suffix == ".fix":
             fn_entrypoint = extract_metadata(file).fn_entrypoint
             harness_ctx = ENTRYPOINT_HARNESS_MAP[fn_entrypoint]
+            context = read_fixture(file).input
         else:
             harness_ctx = HARNESS_MAP[default_harness_ctx]
+            context = read_context(harness_ctx, file)
 
         # Execute and cleanup
-        context = read_context(harness_ctx, file)
         start = time.time()
-        effects = process_target(harness_ctx, lib, serialize_context(harness_ctx, file))
+        effects = process_target(harness_ctx, lib, context)
         end = time.time()
 
         print(f"Total time taken for {file}: {(end - start) * 1000} ms\n------------")