diff --git a/tools/plistutil.c b/tools/plistutil.c
index e439d13..9c503b7 100644
--- a/tools/plistutil.c
+++ b/tools/plistutil.c
@@ -84,8 +84,7 @@
             i++;
             continue;
         }
-
-        if (!strcmp(argv[i], "--outfile") || !strcmp(argv[i], "-o"))
+        else if (!strcmp(argv[i], "--outfile") || !strcmp(argv[i], "-o"))
         {
             if ((i + 1) == argc)
             {
@@ -96,8 +95,7 @@
             i++;
             continue;
         }
-
-        if (!strcmp(argv[i], "--format") || !strcmp(argv[i], "-f"))
+        else if (!strcmp(argv[i], "--format") || !strcmp(argv[i], "-f"))
         {
             if ((i + 1) == argc)
             {
@@ -116,17 +114,21 @@
             i++;
             continue;
         }
-
-        if (!strcmp(argv[i], "--debug") || !strcmp(argv[i], "-d"))
+        else if (!strcmp(argv[i], "--debug") || !strcmp(argv[i], "-d"))
         {
             options->debug = 1;
         }
-
-        if (!strcmp(argv[i], "--help") || !strcmp(argv[i], "-h"))
+        else if (!strcmp(argv[i], "--help") || !strcmp(argv[i], "-h"))
         {
             free(options);
             return NULL;
         }
+        else
+        {
+            printf("ERROR: Invalid option '%s'\n", argv[i]);
+            free(options);
+            return NULL;
+        }
     }
 
     return options;