--- pythia8306.orig/include/Pythia8/PythiaStdlib.h	2021-06-29 16:10:32.000000000 +0200
+++ pythia8306/include/Pythia8/PythiaStdlib.h	2022-01-15 20:36:32.816348346 +0100
@@ -28,6 +28,7 @@
 #include <set>
 #include <list>
 #include <functional>
+#include <type_traits>
 
 // Stdlib header file for dynamic library loading.
 #include <dlfcn.h>
--- pythia8306.orig/include/Pythia8/SusyLesHouches.h	2021-06-29 16:10:32.000000000 +0200
+++ pythia8306/include/Pythia8/SusyLesHouches.h	2022-01-15 22:28:37.409356450 +0100
@@ -65,13 +65,28 @@
       ? true : false;};
 
     // Indexing with (). Output only.
-    T operator()() {
+    template<class Q = T>
+    typename std::enable_if<std::is_arithmetic<Q>::value, Q>::type
+    operator()() {
       if (exists(0)) {return entry[0];} else {T dummy(0); return dummy;};
     };
-    T operator()(int iIn) {
+    template<class Q = T>
+    typename std::enable_if<std::is_arithmetic<Q>::value, Q>::type
+    operator()(int iIn) {
       if (exists(iIn)) {return entry[iIn];} else {T dummy(0); return dummy;};
     };
 
+    template<class Q = T>
+    typename std::enable_if<!std::is_arithmetic<Q>::value, Q>::type
+    operator()() {
+      if (exists(0)) {return entry[0];} else {T dummy; return dummy;};
+    };
+    template<class Q = T>
+    typename std::enable_if<!std::is_arithmetic<Q>::value, Q>::type
+    operator()(int iIn) {
+      if (exists(iIn)) {return entry[iIn];} else {T dummy; return dummy;};
+    };
+
     // Size of map
     int size() {return int(entry.size());};