diff --git a/src/substrait/common/Io.cpp b/src/substrait/common/Io.cpp
index aa315b24..51b2ec61 100644
--- a/src/substrait/common/Io.cpp
+++ b/src/substrait/common/Io.cpp
@@ -54,6 +54,7 @@ absl::StatusOr<::substrait::proto::Plan> loadPlanWithUnknownEncoding(
     case kText:
       return textplan::loadFromText(*contentOrError);
   }
+  return absl::UnimplementedError("Unexpected encoding requested.");
 }
 
 absl::Status savePlan(
@@ -70,6 +71,7 @@ absl::Status savePlan(
     case kText:
       return textplan::savePlanToText(plan, output_filename);
   }
+  return absl::UnimplementedError("Unexpected encoding requested.");
 }
 
 } // namespace io::substrait
diff --git a/src/substrait/textplan/StringManipulation.h b/src/substrait/textplan/StringManipulation.h
index b570a587..d0d602e6 100644
--- a/src/substrait/textplan/StringManipulation.h
+++ b/src/substrait/textplan/StringManipulation.h
@@ -2,7 +2,9 @@
 
 #pragma once
 
+#include <string>
 #include <string_view>
+#include <vector>
 
 namespace io::substrait::textplan {