diff --git a/readLib/source/Interface.dummy.cc b/readLib/source/Interface.dummy.cc
index a84753f56b3644c88a6f1d9ce4502c2cacf2f468..74d7040e6793634f1a6d70431bd8a66e4799e7cb 100644
--- a/readLib/source/Interface.dummy.cc
+++ b/readLib/source/Interface.dummy.cc
@@ -41,7 +41,7 @@ namespace corsika_data {
 
   // the fortran interface functions
   extern "C" {
-  void cordataopenfile_(const char* name, const int stringlength) {
+  void cordataopenfile_(const char* name, const int) {
     CorDataOpenFile(name);
   }
   void cordatafillarray_(double* data, const int& length) {