diff --git a/backend/src/main/resources/db/migration/V18__add_transcription_blocks.sql b/backend/src/main/resources/db/migration/V18__add_transcription_blocks.sql
index 524a2649..94fc30de 100644
--- a/backend/src/main/resources/db/migration/V18__add_transcription_blocks.sql
+++ b/backend/src/main/resources/db/migration/V18__add_transcription_blocks.sql
@@ -2,7 +2,7 @@ CREATE TABLE transcription_blocks (
     id            UUID             PRIMARY KEY DEFAULT gen_random_uuid(),
     annotation_id UUID             NOT NULL REFERENCES document_annotations(id) ON DELETE RESTRICT,
     document_id   UUID             NOT NULL REFERENCES documents(id) ON DELETE CASCADE,
-    text          TEXT             NOT NULL DEFAULT '',
+    text          TEXT             NOT NULL DEFAULT '' CHECK (length(text) <= 10000),
     label         VARCHAR(200),
     sort_order    INTEGER          NOT NULL DEFAULT 0,
     version       INTEGER          NOT NULL DEFAULT 0,