#include "builtin.h"
+#include "cache.h"
 #include "attr.h"
 #include "quote.h"
 
        struct git_attr_check *check;
        int cnt, i, doubledash;
 
+       if (read_cache() < 0) {
+               die("invalid cache");
+       }
+
        doubledash = -1;
        for (i = 1; doubledash < 0 && i < argc; i++) {
                if (!strcmp(argv[i], "--"))
        check = xcalloc(cnt, sizeof(*check));
        for (i = 0; i < cnt; i++) {
                const char *name;
+               struct git_attr *a;
                name = argv[i + 1];
-               check[i].attr = git_attr(name, strlen(name));
+               a = git_attr(name, strlen(name));
+               if (!a)
+                       return error("%s: not a valid attribute name", name);
+               check[i].attr = a;
        }
 
        for (i = doubledash; i < argc; i++) {
                if (git_checkattr(argv[i], cnt, check))
                        die("git_checkattr died");
                for (j = 0; j < cnt; j++) {
+                       const char *value = check[j].value;
+
+                       if (ATTR_TRUE(value))
+                               value = "set";
+                       else if (ATTR_FALSE(value))
+                               value = "unset";
+                       else if (ATTR_UNSET(value))
+                               value = "unspecified";
+
                        write_name_quoted("", 0, argv[i], 1, stdout);
-                       printf(": %s: %s\n", argv[j+1],
-                              (check[j].isset < 0) ? "unspecified" :
-                              (check[j].isset == 0) ? "unset" :
-                              "set");
+                       printf(": %s: %s\n", argv[j+1], value);
                }
        }
        return 0;