diff --git a/src/main.c b/src/main.c
index 660f2eb..aa141b6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -16,12 +16,18 @@ int main(int argc, char *argv[]) {
         }
         if (!strcmp(argv[i], "--x")) {
             if (argc >= i) {
-                size_x = atoi(argv[i + 1]);
+                if(sscanf(argv[i+1], "%d", &size_x) != 1){
+                    printf("invalid input\n");
+                    return 1;
+                }
             }
         }
         if (!strcmp(argv[i], "--y")) {
             if (argc >= i) {
-                size_y = atoi(argv[i + 1]);
+                if(sscanf(argv[i+1], "%d", &size_y) != 1){
+                    printf("invalid input\n");
+                    return 1;
+                }
             }
         }
     }