diff --git a/library/src/calculator_functions.cpp b/library/src/calculator_functions.cpp
index c8eea44..6c45218 100644
--- a/library/src/calculator_functions.cpp
+++ b/library/src/calculator_functions.cpp
@@ -271,14 +271,19 @@ std::string Calculator::GetDurationFromCost(Configuration* cfg,
 	cout << "Total minutes: " << (int)ret_val << endl;
     if (ret_val <= 0) return "PARKING NOT ALLOWED";
 
-#if !defined(_SVID_SOURCE) && !defined(_XOPEN_SOURCE)
-    // needed for timezone-correction
-    #error "!defined(_SVID_SOURCE) && !defined(_XOPEN_SOURCE)"
-#else
-    // timezone correction: localtime() needs argument in UTC-timezone
-    // The global variable 'timezone' is set by tzset(), see
-    // https://linux.die.net/man/3/tzset, so I change of the timezone will
-    // also change the value of the variable 'timezone'.
+#ifdef __linux__
+    #if !defined(_SVID_SOURCE) && !defined(_XOPEN_SOURCE)
+        // needed for timezone-correction
+        #error "!defined(_SVID_SOURCE) && !defined(_XOPEN_SOURCE)"
+    #else
+        // timezone correction: localtime() needs argument in UTC-timezone
+        // The global variable 'timezone' is set by tzset(), see
+        // https://linux.die.net/man/3/tzset, so I change of the timezone will
+        // also change the value of the variable 'timezone'.
+        valid_until_datetime_t += timezone;
+    #endif
+#else // windows, only for testing
+    static const long timezone = -3600;
     valid_until_datetime_t += timezone;
 #endif