diff --git a/cpp/src/arrow/ipc/metadata_internal.cc b/cpp/src/arrow/ipc/metadata_internal.cc
index 10cee49963e..5bb1eddc1ea 100644
--- a/cpp/src/arrow/ipc/metadata_internal.cc
+++ b/cpp/src/arrow/ipc/metadata_internal.cc
@@ -428,8 +428,7 @@ static Status GetDictionaryEncoding(FBB& fbb, const std::shared_ptr<Field>& fiel
                                     const DictionaryType& type, int64_t dictionary_id,
                                     DictionaryOffset* out) {
   // We assume that the dictionary index type (as an integer) has already been
-  // validated elsewhere, and can safely assume we are dealing with signed
-  // integers
+  // validated elsewhere, and can safely assume we are dealing with integers
   const auto& index_type = checked_cast<const IntegerType&>(*type.index_type());
 
   auto index_type_offset =