diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2d5bf8a..a51d9be 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # CHANGELOG
 
+### Bug fix
+
+ * Add argument to `--svg-topurl` in help message.
+
 ## v1.4.2 (2024-09-23)
 
 ### Features
diff --git a/README.md b/README.md
index d92ff00..5ec8638 100644
--- a/README.md
+++ b/README.md
@@ -24,7 +24,9 @@ One of the standout features of this tool is the ability to generate class diagr
 To enable this feature, generate the diagrams in SVG format and use the `--svg-topurl` option to specify the base URL for the links:
 
 ```shell
-$ vendor/bin/php-class-diagram --svg-topurl='https://github.com/your-username/your-repo/blob/main/path/to/source' path/to/php/files
+$ vendor/bin/php-class-diagram \
+    --svg-topurl='https://github.com/your-username/your-repo/blob/main/path/to/source' \
+    path/to/php/files
 ```
 
 To embed the SVG diagrams in HTML while preserving the clickable links, use the `embed` or `object` tags instead of `img`. Here’s an example:
@@ -113,7 +115,7 @@ OPTIONS
       --hide-private               hide private properties and methods.
       --hide-private-properties    hide private properties.
       --hide-private-methods       hide private methods.
-      --svg-topurl                 specifies the top URL when displaying the class as a link when outputting in SVG format.
+      --svg-topurl='url'           Specifies the top URL when displaying the class as a link when outputting in SVG format.
       --header='header string'     additional header string. You can specify multiple header values.
       --include='wildcard'         include target file pattern. (default: `*.php`) You can specify multiple include patterns.
       --exclude='wildcard'         exclude target file pattern. You can specify multiple exclude patterns.
diff --git a/bin/php-class-diagram b/bin/php-class-diagram
index 62b879f..63bc72d 100755
--- a/bin/php-class-diagram
+++ b/bin/php-class-diagram
@@ -61,7 +61,7 @@ OPTIONS
       --hide-private               hide private properties and methods.
       --hide-private-properties    hide private properties.
       --hide-private-methods       hide private methods.
-      --svg-topurl                 Specifies the top URL when displaying the class as a link when outputting in SVG format.
+      --svg-topurl='url'           Specifies the top URL when displaying the class as a link when outputting in SVG format.
       --header='header string'     additional header string. You can specify multiple header values.
       --include='wildcard'         include target file pattern. (default: `*.php`) You can specify multiple include patterns.
       --exclude='wildcard'         exclude target file pattern. You can specify multiple exclude patterns.