diff --git a/standards/php.md b/standards/php.md
index a72d6df..b862ca6 100644
--- a/standards/php.md
+++ b/standards/php.md
@@ -36,6 +36,10 @@ Php code embedded into template files SHOULD use the alternative syntax for cont
 <?php endif; ?>
 ```
 
+## Strings
+
+Strings must use single quotes `'` instead of `"` unless double quotes are required.
+
 ## Echo
 
 when echoing multiple components, don't concat them but use `,`.
@@ -155,4 +159,4 @@ The usage of the following functions SHOULD be avoided and inspected for any kin
 * `rmdir()`
 * `mkdir()`
 * `touch()`
-* `unlink()`
\ No newline at end of file
+* `unlink()`