diff --git a/include/flags.h b/include/flags.h
index afee89d..95de818 100644
--- a/include/flags.h
+++ b/include/flags.h
@@ -35,10 +35,10 @@ typedef struct
 } outputFlags;
 
 //VARIABLES
-static int keyLength = 50; //LENGTH OF KEY     > DO NOT TOUCH THIS <
+static unsigned long keyLength = 50; //LENGTH OF KEY     > DO NOT TOUCH THIS <
 
 //GETTERS
-int getKeyLength();
+unsigned long getKeyLength();
 inputFlags noFlags(); //THIS GENERATES inputFlags WITH DEFAULT VALUES
 
 //SETTERS
diff --git a/src/lib/flags.c b/src/lib/flags.c
index 951b203..09c2c8c 100644
--- a/src/lib/flags.c
+++ b/src/lib/flags.c
@@ -1,6 +1,6 @@
 #include <why2/flags.h>
 
-int getKeyLength()
+unsigned long getKeyLength()
 {
     return keyLength;
 }
diff --git a/src/lib/misc.c b/src/lib/misc.c
index f7b89de..ca8b272 100644
--- a/src/lib/misc.c
+++ b/src/lib/misc.c
@@ -177,7 +177,7 @@ void checkKey(char *key, inputFlags flags)
 {
     if (strlen(key) < getKeyLength())
     {
-        if (!flags.noOutput) fprintf(stderr, "Key must be at least %d characters long!\n", getKeyLength());
+        if (!flags.noOutput) fprintf(stderr, "Key must be at least %lu characters long!\n", getKeyLength());
         exit(INVALID_KEY);
     }
 }