diff --git a/hallo b/hallo
index e53e9fc..8883a6d 100755
Binary files a/hallo and b/hallo differ
diff --git a/hallo-welt.c b/hallo-welt.c
index 640887b..0433806 100644
--- a/hallo-welt.c
+++ b/hallo-welt.c
@@ -1,4 +1,5 @@
 #include "hallo-welt.h"
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -9,14 +10,22 @@
 
 void hallo_welt(void) { printf(HALLO); }
 
+int zweierkomplement(int32_t i) { return ~i + 1; }
+
 // use more then one int type
-const char *binaerzahl(uint32_t bin) {
+const char *binaerzahl(int32_t bin) {
   char *str = malloc(sizeof(bin) * 8 +
                      1); // Allocate 8 bits for actual data and 1 Bit for the \0
                          // sign indicating the end of the string
+  bool is_negative;
   if (!str)
     return NULL;
-  uint8_t bb;
+  if (bin < 0) {
+    bin = zweierkomplement(bin);
+    is_negative = true;
+  }
+  int32_t bb; // that way we keep the memory lighter
+  printf(is_negative ? "-" : "");
   for (int i = sizeof(bin) * 8 - 1; i >= 0; i--) {
     bb = bin >> i;
     str[i] = (bb % 2 == 1) ? 1 : 0;
@@ -28,6 +37,7 @@ const char *binaerzahl(uint32_t bin) {
 
 int getint(void) {
   uint32_t i;
+  printf("Geben Sie eine Dezimahlzahl ein: ");
   scanf("%u", &i);
   return i;
 }