diff --git a/du3/program.c b/du3/program.c
index 4be63f7..b9832b4 100644
--- a/du3/program.c
+++ b/du3/program.c
@@ -86,6 +86,11 @@ int main() {
                 result = a * b;
             }
             if (strcmp(input, "/")==0) {
+                if (b==0) {
+                    printf("0!\n");
+                    destroy_stack(s);
+                    return 0;
+                }
                 result = a/b;
             }
             push_stack(s, result);