diff --git a/README.md b/README.md
index f8b8403..0fd7b92 100644
--- a/README.md
+++ b/README.md
@@ -42,3 +42,13 @@ session.execute(
     sql"SELECT * FROM test".query(crypt.text ~ crypt.int4)
 )
 ```
+
+All columns intended for storing encrypted data must be of type `TEXT` in the database.
+
+e.g.:
+```sql
+CREATE TABLE test (
+    string TEXT,
+    numbers TEXT
+)
+```
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