diff --git a/makefile b/makefile
index daef398..4d3e330 100644
--- a/makefile
+++ b/makefile
@@ -1,2 +1,2 @@
 all:
-	gcc quadratic.c -lm -o "bin-quadratic.out"
+	gcc quadratic.c -lm -Wall -O3 -o "bin-quadratic.out"
diff --git a/quadratic.c b/quadratic.c
index 5d2155f..00c05c2 100644
--- a/quadratic.c
+++ b/quadratic.c
@@ -2,7 +2,7 @@
 #include <stdlib.h>
 #include <math.h>
 
-void main()
+int main()
 {
     system("clear");
     printf("\n ~~ Quadratic Calculator ~~\n");
@@ -43,4 +43,5 @@ void main()
 
         printf("The zeros are: %f and %f.\n", zero_1_ptr, zero_2_ptr);
     };
+    return 0;
 };