diff --git a/dtls/client-dtls-nonblocking.c b/dtls/client-dtls-nonblocking.c
index 90246824..986b289d 100644
--- a/dtls/client-dtls-nonblocking.c
+++ b/dtls/client-dtls-nonblocking.c
@@ -62,7 +62,7 @@ int main (int argc, char** argv)
     char*               srTest = "testing session resume";
 
     if (argc != 2) {
-	    printf("usage: udpcli <IP address>\n");
+        printf("usage: udpcli <IP address>\n");
         return 1;
     }