diff --git a/.changeset/gentle-results-lie.md b/.changeset/gentle-results-lie.md
new file mode 100644
index 0000000000..0c53407db3
--- /dev/null
+++ b/.changeset/gentle-results-lie.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-techdocs': patch
+---
+
+Fixed schema type for additionalAllowedURIProtocols
diff --git a/plugins/techdocs/config.d.ts b/plugins/techdocs/config.d.ts
index 584d340fbf..0e9b7abdda 100644
--- a/plugins/techdocs/config.d.ts
+++ b/plugins/techdocs/config.d.ts
@@ -67,7 +67,7 @@ export interface Config {
        *  @see: https://raw.githubusercontent.com/cure53/DOMPurify/master/src/regexp.ts
        * @visibility frontend
        */
-      additionalAllowedURIProtocols?: string;
+      additionalAllowedURIProtocols?: string[];
     };
   };
 }