diff --git a/export/planloader/CMakeLists.txt b/export/planloader/CMakeLists.txt
index 00064846..13eceabe 100644
--- a/export/planloader/CMakeLists.txt
+++ b/export/planloader/CMakeLists.txt
@@ -1,7 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
-
 if(NOT BUILD_SUBDIR_NAME EQUAL "release")
   message(
     SEND_ERROR,
@@ -10,7 +8,6 @@ if(NOT BUILD_SUBDIR_NAME EQUAL "release")
 endif()
 
 add_library(planloader SHARED planloader.cpp)
-set_target_properties(planloader PROPERTIES SUBVERSION 1)
 
 add_dependencies(planloader substrait_io)
 target_link_libraries(planloader substrait_io)
diff --git a/export/planloader/planloader.cpp b/export/planloader/planloader.cpp
index 4ce6ae39..00d3d204 100644
--- a/export/planloader/planloader.cpp
+++ b/export/planloader/planloader.cpp
@@ -10,23 +10,23 @@ extern "C" {
 // Load a Substrait plan (in any format) from disk.
 // Stores the Substrait plan in planBuffer in serialized form.
 // Returns a SerializedPlan structure containing either the serialized plan or
-// an error message.  errorMessage is nullptr upon success.
+// an error message.  error_message is nullptr upon success.
 SerializedPlan* load_substrait_plan(const char* filename) {
   auto newPlan = new SerializedPlan();
   newPlan->buffer = nullptr;
   newPlan->size = 0;
-  newPlan->errorMessage = nullptr;
+  newPlan->error_message = nullptr;
 
   auto planOrError = io::substrait::loadPlan(filename);
   if (!planOrError.ok()) {
     auto errMsg = planOrError.status().message();
-    newPlan->errorMessage = new char[errMsg.length()+1];
-    strncpy(newPlan->errorMessage, errMsg.data(), errMsg.length()+1);
+    newPlan->error_message = new char[errMsg.length()+1];
+    strncpy(newPlan->error_message, errMsg.data(), errMsg.length()+1);
     return newPlan;
   }
   ::substrait::proto::Plan plan = *planOrError;
   std::string text = plan.SerializeAsString();
-  newPlan->buffer = new char[text.length()+1];
+  newPlan->buffer = new unsigned char[text.length()+1];
   memcpy(newPlan->buffer, text.data(), text.length()+1);
   newPlan->size = static_cast<int32_t>(
             text.length() &
@@ -36,7 +36,7 @@ SerializedPlan* load_substrait_plan(const char* filename) {
 
 void free_substrait_plan(SerializedPlan* plan) {
   delete[] plan->buffer;
-  delete[] plan->errorMessage;
+  delete[] plan->error_message;
   delete plan;
 }
 
@@ -44,12 +44,12 @@ void free_substrait_plan(SerializedPlan* plan) {
 // On error returns a non-empty error message.
 // On success a nullptr is returned.
 const char* save_substrait_plan(
-    const char* planData,
-    uint32_t planDataLength,
+    const unsigned char* plan_data,
+    uint32_t plan_data_length,
     const char* filename,
     io::substrait::PlanFileFormat format) {
   ::substrait::proto::Plan plan;
-  std::string data(planData, planDataLength);
+  std::string data((const char*) plan_data, plan_data_length);
   plan.ParseFromString(data);
   auto result = io::substrait::savePlan(plan, filename, format);
   if (!result.ok()) {
diff --git a/export/planloader/planloader.h b/export/planloader/planloader.h
index 8c3d4beb..1c46fccf 100644
--- a/export/planloader/planloader.h
+++ b/export/planloader/planloader.h
@@ -6,31 +6,38 @@ extern "C" {
 
 using SerializedPlan = struct {
   // If set, contains a serialized ::substrait::proto::Plan object.
-  char *buffer;
+  unsigned char *buffer;
   // If buffer is set, this is the size of the buffer.
   int32_t size;
   // If null the buffer is valid, otherwise this points to a null terminated
   // error string.
-  char *errorMessage;
+  char *error_message;
 };
 
 // Since this is actually C code, stick to C style names for exporting.
 // NOLINTBEGIN(readability-identifier-naming)
 
 // Load a Substrait plan (in any format) from disk.
-// Stores the Substrait plan in planBuffer in serialized form.
+//
+// Accepts filename as a null-terminated C string.
 // Returns a SerializedPlan structure containing either the serialized plan or
-// an error message.
+// an error message.  This SerializedPlan should be freed using
+// free_substrait_plan.
 SerializedPlan* load_substrait_plan(const char* filename);
 
+// Frees a SerializedPlan that was returned from load_substrait_plan.
 void free_substrait_plan(SerializedPlan* plan);
 
 // Write a serialized Substrait plan to disk in the specified format.
+//
+// plan_data is a Substrait Plan serialized into a byte array with length
+// plan_data_length.
+// Filename is a null-terminated C string.
 // On error returns a non-empty error message.
 // On success an empty string is returned.
 const char* save_substrait_plan(
-    const char* planData,
-    uint32_t planDataLength,
+    const unsigned char* plan_data,
+    uint32_t plan_data_length,
     const char* filename,
     io::substrait::PlanFileFormat format);
 
diff --git a/export/planloader/tests/PlanLoaderTest.cpp b/export/planloader/tests/PlanLoaderTest.cpp
index 4216bf10..4cbe6db5 100644
--- a/export/planloader/tests/PlanLoaderTest.cpp
+++ b/export/planloader/tests/PlanLoaderTest.cpp
@@ -11,7 +11,7 @@ namespace {
 
 TEST(PlanLoaderTest, LoadAndSave) {
   auto serializedPlan = load_substrait_plan("data/q6_first_stage.json");
-  ASSERT_EQ(serializedPlan->errorMessage, nullptr);
+  ASSERT_EQ(serializedPlan->error_message, nullptr);
 
   ::substrait::proto::Plan plan;
   bool parseStatus =