diff --git a/dice/src/dice.c b/dice/src/dice.c
index 9a1994f..926733a 100644
--- a/dice/src/dice.c
+++ b/dice/src/dice.c
@@ -7,6 +7,8 @@
 
 #include <dice.h>
 
+static bool prefix = false;
+
 static bool evaluate_expression(char const *s)
 {
     dice_expression_t e = dice_expression_new();
@@ -31,7 +33,11 @@ static bool evaluate_expression(char const *s)
         goto error;
     }
 
-    printf("%ld\n", result);
+    if (prefix) {
+        printf("%s: %ld\n", s, result);
+    } else {
+        printf("%ld\n", result);
+    }
 
     ret = true;
 
@@ -43,9 +49,10 @@ error:
 
 int main(int ac, char **av)
 {
-    static char const *optstr = "e:";
+    static char const *optstr = "e:p";
     static struct option opts[] = {
         { "expression", required_argument, NULL, 'e' },
+        { "prefix", no_argument, NULL, 'p' },
         { NULL, 0, NULL, 0}
     };
 
@@ -64,6 +71,8 @@ int main(int ac, char **av)
             }
         } break;
 
+        case 'p': prefix = true; break;
+
         default:
         {
             fprintf(stderr, "invalid option specified\n");
@@ -83,8 +92,8 @@ int main(int ac, char **av)
 
         for (i = optind; i < ac; i++) {
             fprintf(f, "%s", av[i]);
-            if (i < ac) {
-                fputc(' ', f);
+            if (i < ac-1) {
+                putc(' ', f);
             }
         }