diff --git a/src/substrait/common/Io.cpp b/src/substrait/common/Io.cpp
index ba9ed972..aa315b24 100644
--- a/src/substrait/common/Io.cpp
+++ b/src/substrait/common/Io.cpp
@@ -5,6 +5,7 @@
 #include <regex>
 #include <string_view>
 
+#include "substrait/proto/plan.pb.h"
 #include "substrait/textplan/converter/LoadBinary.h"
 #include "substrait/textplan/converter/SaveBinary.h"
 #include "substrait/textplan/parser/LoadText.h"
diff --git a/src/substrait/textplan/StringManipulation.cpp b/src/substrait/textplan/StringManipulation.cpp
index eac3c56a..a0f5b896 100644
--- a/src/substrait/textplan/StringManipulation.cpp
+++ b/src/substrait/textplan/StringManipulation.cpp
@@ -2,18 +2,33 @@
 
 #include "StringManipulation.h"
 
+#include <numeric>
+#include <vector>
+#include <string>
+#include <string_view>
+
 namespace io::substrait::textplan {
 
-// Yields true if the string 'haystack' starts with the string 'needle'.
 bool startsWith(std::string_view haystack, std::string_view needle) {
   return haystack.size() > needle.size() &&
       haystack.substr(0, needle.size()) == needle;
 }
 
-// Returns true if the string 'haystack' ends with the string 'needle'.
 bool endsWith(std::string_view haystack, std::string_view needle) {
   return haystack.size() > needle.size() &&
       haystack.substr(haystack.size() - needle.size(), needle.size()) == needle;
 }
 
+std::string joinLines(
+    std::vector<std::string> lines,
+    std::string_view separator) {
+  auto concatWithSeparator = [separator](std::string a, const std::string& b) {
+    return std::move(a) + std::string(separator) + b;
+  };
+
+  auto result = std::accumulate(
+      std::next(lines.begin()), lines.end(), lines[0], concatWithSeparator);
+  return result;
+}
+
 } // namespace io::substrait::textplan
diff --git a/src/substrait/textplan/StringManipulation.h b/src/substrait/textplan/StringManipulation.h
index 9c24418f..1cc85e39 100644
--- a/src/substrait/textplan/StringManipulation.h
+++ b/src/substrait/textplan/StringManipulation.h
@@ -12,4 +12,9 @@ bool startsWith(std::string_view haystack, std::string_view needle);
 // Returns true if the string 'haystack' ends with the string 'needle'.
 bool endsWith(std::string_view haystack, std::string_view needle);
 
+// Joins a vector of strings into a single string separated by separator.
+std::string joinLines(
+    std::vector<std::string> lines,
+    std::string_view separator="\n");
+
 } // namespace io::substrait::textplan
diff --git a/src/substrait/textplan/converter/LoadBinary.cpp b/src/substrait/textplan/converter/LoadBinary.cpp
index e6ac8fe7..3c6b315b 100644
--- a/src/substrait/textplan/converter/LoadBinary.cpp
+++ b/src/substrait/textplan/converter/LoadBinary.cpp
@@ -14,6 +14,7 @@
 #include <vector>
 
 #include "substrait/proto/plan.pb.h"
+#include "substrait/textplan/StringManipulation.h"
 
 namespace io::substrait::textplan {
 
@@ -82,8 +83,7 @@ absl::StatusOr<::substrait::proto::Plan> loadFromProtoText(
   parser.RecordErrorsTo(&collector);
   if (!parser.ParseFromString(text, &plan)) {
     auto errors = collector.getErrors();
-    return absl::InternalError(
-        std::accumulate(errors.begin(), errors.end(), std::string("\n")));
+    return absl::InternalError(joinLines(errors));
   }
   return plan;
 }
diff --git a/src/substrait/textplan/converter/SaveBinary.cpp b/src/substrait/textplan/converter/SaveBinary.cpp
index dc7a9ff9..77f50109 100644
--- a/src/substrait/textplan/converter/SaveBinary.cpp
+++ b/src/substrait/textplan/converter/SaveBinary.cpp
@@ -9,6 +9,7 @@
 
 #include <google/protobuf/text_format.h>
 #include <google/protobuf/util/json_util.h>
+#include "substrait/textplan/StringManipulation.h"
 #include "substrait/textplan/SymbolTablePrinter.h"
 #include "substrait/textplan/converter/ParseBinary.h"
 
@@ -72,8 +73,7 @@ absl::Status savePlanToText(
   auto result = parseBinaryPlan(plan);
   auto errors = result.getAllErrors();
   if (!errors.empty()) {
-    return absl::UnknownError(
-        std::accumulate(errors.begin(), errors.end(), std::string("\n")));
+    return absl::UnknownError(joinLines(errors));
   }
   stream << SymbolTablePrinter::outputToText(result.getSymbolTable());
   stream.close();
diff --git a/src/substrait/textplan/converter/tests/BinaryToTextPlanConversionTest.cpp b/src/substrait/textplan/converter/tests/BinaryToTextPlanConversionTest.cpp
index cde3c92a..3b0ae97f 100644
--- a/src/substrait/textplan/converter/tests/BinaryToTextPlanConversionTest.cpp
+++ b/src/substrait/textplan/converter/tests/BinaryToTextPlanConversionTest.cpp
@@ -597,9 +597,10 @@ std::vector<TestCase> getTestCases() {
 TEST_P(BinaryToTextPlanConverterTestFixture, Parse) {
   auto [name, input, matcher] = GetParam();
 
-  auto planOrError = loadFromText(input);
+  auto planOrError = loadFromProtoText(input);
   if (!planOrError.ok()) {
-    ParseResult result(SymbolTable(), planOrError.errors(), {});
+    ParseResult result(
+        SymbolTable(), {std::string(planOrError.status().message())}, {});
     ASSERT_THAT(result, matcher);
     return;
   }
@@ -627,13 +628,15 @@ INSTANTIATE_TEST_SUITE_P(
 class BinaryToTextPlanConversionTest : public ::testing::Test {};
 
 TEST_F(BinaryToTextPlanConversionTest, FullSample) {
-  std::string json = readFromFile("data/q6_first_stage.json");
-  auto planOrError = loadFromJson(json);
+  auto jsonOrError = readFromFile("data/q6_first_stage.json");
+  ASSERT_TRUE(jsonOrError.ok());
+  auto planOrError = loadFromJson(*jsonOrError);
   ASSERT_TRUE(planOrError.ok());
   auto plan = *planOrError;
   EXPECT_THAT(plan.extensions_size(), ::testing::Eq(7));
 
-  std::string expectedOutput = readFromFile("data/q6_first_stage.golden.splan");
+  auto expectedOutputOrError = readFromFile("data/q6_first_stage.golden.splan");
+  ASSERT_TRUE(expectedOutputOrError.ok());
 
   auto result = parseBinaryPlan(plan);
   auto symbols = result.getSymbolTable().getSymbols();
@@ -668,7 +671,7 @@ TEST_F(BinaryToTextPlanConversionTest, FullSample) {
                   SymbolType::kSource,
                   SymbolType::kSchema,
               }),
-          WhenSerialized(EqSquashingWhitespace(expectedOutput))))
+          WhenSerialized(EqSquashingWhitespace(*expectedOutputOrError))))
       << result.getSymbolTable().toDebugString();
 }
 
diff --git a/src/substrait/textplan/parser/LoadText.cpp b/src/substrait/textplan/parser/LoadText.cpp
index 59af341f..ee2c7078 100644
--- a/src/substrait/textplan/parser/LoadText.cpp
+++ b/src/substrait/textplan/parser/LoadText.cpp
@@ -3,6 +3,7 @@
 #include "substrait/textplan/parser/LoadText.h"
 
 #include "substrait/proto/plan.pb.h"
+#include "substrait/textplan/StringManipulation.h"
 #include "substrait/textplan/SymbolTablePrinter.h"
 #include "substrait/textplan/parser/ParseText.h"
 
@@ -13,8 +14,7 @@ absl::StatusOr<::substrait::proto::Plan> loadFromText(std::string_view text) {
   auto parseResult = io::substrait::textplan::parseStream(stream);
   if (!parseResult.successful()) {
     auto errors = parseResult.getAllErrors();
-    return absl::UnknownError(
-        std::accumulate(errors.begin(), errors.end(), std::string("\n")));
+    return absl::UnknownError(joinLines(errors));
   }
 
   return SymbolTablePrinter::outputToBinaryPlan(parseResult.getSymbolTable());