diff --git a/ampel-firmware/csv_writer.cpp b/ampel-firmware/csv_writer.cpp
index 2a673a83b3fbd2eba28297dbd89ebb5629d80fed..db3b22e71713352c92a9be22b6e6ca078d36184f 100644
--- a/ampel-firmware/csv_writer.cpp
+++ b/ampel-firmware/csv_writer.cpp
@@ -118,7 +118,7 @@ namespace csv_writer {
     Serial.println();
 
     sensor_commands::defineIntCallback("csv", setCSVinterval, " 60 (Sets CSV writing interval, in s)");
-    sensor_commands::defineCallback("format_filesystem", formatFilesystem, "(Deletes the whole filesystem.)");
+    sensor_commands::defineCallback("format_filesystem", formatFilesystem, " (Deletes the whole filesystem.)");
   }
 
   File openOrCreate() {
diff --git a/ampel-firmware/sensor_commands.cpp b/ampel-firmware/sensor_commands.cpp
index c6bd77cb7e37533f7fe3299ddf2fae7640306707..4401b344c657fdd5435744fad84a1694f5908a5f 100644
--- a/ampel-firmware/sensor_commands.cpp
+++ b/ampel-firmware/sensor_commands.cpp
@@ -5,24 +5,35 @@ namespace sensor_commands {
   const uint8_t MAX_COMMAND_SIZE = 30;
 
   uint8_t callbacks_count = 0;
+
   struct Callback {
-    Callback(const char *s = 0, void (*f)(int32_t) = 0, const char *d = 0) :
-        name(s), function(f), doc(d) {
-    }
     const char *name;
-    void (*function)(int32_t);
+    union {
+      void (*intFunction)(int32_t);
+      void (*voidFunction)(void);
+    };
     const char *doc;
   };
 
   Callback callbacks[MAX_CALLBACKS];
 
+  //NOTE: Probably possible to DRY
   void defineCallback(const char *name, void (*function)(void), const char *doc) {
-
+    if (callbacks_count < MAX_CALLBACKS) {
+      callbacks[callbacks_count].name = name;
+      callbacks[callbacks_count].voidFunction = function;
+      callbacks[callbacks_count].doc = doc;
+      callbacks_count++;
+    } else {
+      Serial.println(F("Too many callbacks have been defined."));
+    }
   }
 
   void defineIntCallback(const char *name, void (*function)(int32_t), const char *doc) {
     if (callbacks_count < MAX_CALLBACKS) {
-      callbacks[callbacks_count] = Callback(name, function, doc);
+      callbacks[callbacks_count].name = name;
+      callbacks[callbacks_count].intFunction = function;
+      callbacks[callbacks_count].doc = doc;
       callbacks_count++;
     } else {
       Serial.println(F("Too many callbacks have been defined."));
@@ -81,7 +92,7 @@ namespace sensor_commands {
         Serial.print("(");
         Serial.print(parameter);
         Serial.println(")");
-        callbacks[i].function(parameter);
+        callbacks[i].intFunction(parameter);
         return;
       }
     }