diff --git a/docs/README.md b/docs/README.md
index c54c22610..86a742f8d 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -716,6 +716,8 @@ An add column operation creates a new column on an existing table.
 }
 ```
 
+Default values are subject to the usual rules for quoting SQL expressions. In particular, string literals should be surrounded with single quotes.
+
 Example **add column** migrations:
 
 * [03_add_column.json](../examples/03_add_column.json)
@@ -924,6 +926,8 @@ where each `column` is defined as:
 },
 ```
 
+Default values are subject to the usual rules for quoting SQL expressions. In particular, string literals should be surrounded with single quotes.
+
 Example **create table** migrations:
 
 * [01_create_tables.json](../examples/01_create_tables.json)