diff --git a/src/backend/commands/copyfromparse.c b/src/backend/commands/copyfromparse.c
index edb80e2cd5..e06534943f 100644
--- a/src/backend/commands/copyfromparse.c
+++ b/src/backend/commands/copyfromparse.c
@@ -444,7 +444,7 @@ CopyConvertBuf(CopyFromState cstate)
 			 * least one character, and a failure to do so means that we've
 			 * hit an invalid byte sequence.
 			 */
-			if (cstate->raw_reached_eof || unverifiedlen >= pg_database_encoding_max_length())
+			if (cstate->raw_reached_eof || unverifiedlen >= pg_encoding_max_length(cstate->file_encoding))
 				cstate->input_reached_error = true;
 			return;
 		}
@@ -1172,14 +1172,12 @@ CopyReadLineText(CopyFromState cstate)
 		char		c;
 
 		/*
-		 * Load more data if needed.  Ideally we would just force four bytes
-		 * of read-ahead and avoid the many calls to
-		 * IF_NEED_REFILL_AND_NOT_EOF_CONTINUE(), but the COPY_OLD_FE protocol
-		 * does not allow us to read too far ahead or we might read into the
-		 * next data, so we read-ahead only as far we know we can.  One
-		 * optimization would be to read-ahead four byte here if
-		 * cstate->copy_src != COPY_OLD_FE, but it hardly seems worth it,
-		 * considering the size of the buffer.
+		 * Load more data if needed.
+		 *
+		 * TODO: We could just force four bytes of read-ahead and avoid the
+		 * many calls to IF_NEED_REFILL_AND_NOT_EOF_CONTINUE().  That was
+		 * unsafe with the old v2 COPY protocol, but we don't support that
+		 * anymore.
 		 */
 		if (input_buf_ptr >= copy_buf_len || need_data)
 		{
@@ -1214,9 +1212,6 @@ CopyReadLineText(CopyFromState cstate)
 			 * Force fetch of the next character if we don't already have it.
 			 * We need to do this before changing CSV state, in case one of
 			 * these characters is also the quote or escape character.
-			 *
-			 * Note: old-protocol does not like forced prefetch, but it's OK
-			 * here since we cannot validly be at EOF.
 			 */
 			if (c == '\\' || c == '\r')
 			{