diff --git a/libxslt/extensions.c b/libxslt/extensions.c
index 1234567..abcdefg 100644
--- a/libxslt/extensions.c
+++ b/libxslt/extensions.c
@@ -2245,7 +2245,7 @@ xsltRegisterTestModule(void) {
 static void
 xsltHashScannerModuleFree(void *payload ATTRIBUTE_UNUSED,
                           void *data ATTRIBUTE_UNUSED,
-                          xmlChar * name ATTRIBUTE_UNUSED)
+                          const xmlChar * name ATTRIBUTE_UNUSED)
 {
 #ifdef WITH_MODULES
     xmlModuleClose(payload);