diff --git a/collects/scribblings/reference/startup.scrbl b/collects/scribblings/reference/startup.scrbl
index fcca28afc8..c38310af17 100644
--- a/collects/scribblings/reference/startup.scrbl
+++ b/collects/scribblings/reference/startup.scrbl
@@ -242,7 +242,12 @@ flags:
   @item{@FlagFirst{X} @nonterm{dir} or @DFlagFirst{collects}
         @nonterm{dir} : Sets @nonterm{dir} as the path to the main
         collection of libraries by making @racket[(find-system-path
-        'collects-dir)] produce @nonterm{dir}.}
+        'collects-dir)] produce @nonterm{dir}. If @nonterm{dir} is an
+        empty string, then @racket[(find-system-path 'collects-dir)]
+        returns @filepath{.}, but
+        @racket[current-library-collection-paths] is initialized to
+        the empty list and @racket[use-collection-link-paths] is
+        initialized to @racket[#f].}
 
   @item{@FlagFirst{S} @nonterm{dir} or @DFlagFirst{search}
         @nonterm{dir} : Adds @nonterm{dir} to the default library
diff --git a/src/racket/cmdline.inc b/src/racket/cmdline.inc
index 8fd36f5f7a..3372ca2af3 100644
--- a/src/racket/cmdline.inc
+++ b/src/racket/cmdline.inc
@@ -860,7 +860,11 @@ static int run_from_cmd_line(int argc, char *_argv[],
 	  }
 	  argv++;
 	  --argc;
-	  collects_path = check_make_path(prog, real_switch, argv[0]);
+          if (!*(argv[0])) {
+            /* #f => no collects path */
+            collects_path = scheme_false;
+          } else
+            collects_path = check_make_path(prog, real_switch, argv[0]);
           was_config_flag = 1;
 	  break;
 	case 'A':
@@ -1175,16 +1179,19 @@ static int run_from_cmd_line(int argc, char *_argv[],
 #ifndef NO_FILE_SYSTEM_UTILS
   /* Setup path for "collects" collection directory: */
   if (!collects_path) {
-    if (!_coldir[_coldir_offset]) {
-      /* empty list of directories => don't set collection dirs
-         and don't use collection links files */
-      skip_coll_dirs = 1;
-      scheme_set_ignore_link_paths(1);
-      collects_path = scheme_make_path(".");
-    } else
+    if (!_coldir[_coldir_offset])
+      collects_path = scheme_false;
+    else
       collects_path = scheme_make_path(_coldir XFORM_OK_PLUS _coldir_offset);
-  } else
+  } else if (!SCHEME_FALSEP(collects_path))
     collects_path = scheme_path_to_complete_path(collects_path, NULL);
+  if (SCHEME_FALSEP(collects_path)) {
+    /* empty list of directories => don't set collection dirs
+       and don't use collection links files */
+    skip_coll_dirs = 1;
+    scheme_set_ignore_link_paths(1);
+    collects_path = scheme_make_path(".");
+  }
   scheme_set_collects_path(collects_path);
 
   /* Make list of additional collection paths: */
@@ -1343,7 +1350,7 @@ static int run_from_cmd_line(int argc, char *_argv[],
 	 "  -z, --text-repl : Use text `read-eval-print-loop' for -i\n"
 # endif
          "  -I <path> : Set <init-lib> to <path>\n"
-	 "  -X <dir>, --collects <dir> : Main collects at <dir>\n"
+	 "  -X <dir>, --collects <dir> : Main collects at <dir> (or \"\" disables all)\n"
 	 "  -S <dir>, --search <dir> : More collects at <dir> (after main collects)\n"
 	 "  -A <dir>, --addon <dir> : Addon directory at <dir>\n"
 	 "  -K <file>, --links <file> : User-specific collection links at <file>\n"