diff --git a/docs/sophia_syntax.md b/docs/sophia_syntax.md
index 3f9d84f..0f7aa07 100644
--- a/docs/sophia_syntax.md
+++ b/docs/sophia_syntax.md
@@ -18,7 +18,7 @@ interface main using as for hiding
 ### Tokens
 
 - `Id = [a-z_][A-Za-z0-9_']*` identifiers start with a lower case letter.
-- `Con = [A-Z][A-Za-z0-9_']*` constructors start with an upper case letter.
+- `Con = [A-Z][A-Za-z0-9_]*` constructors start with an upper case letter.
 - `QId = (Con\.)+Id` qualified identifiers (e.g. `Map.member`)
 - `QCon = (Con\.)+Con` qualified constructor
 - `TVar = 'Id` type variable (e.g `'a`, `'b`)