diff --git a/collects/planet2/lib.rkt b/collects/planet2/lib.rkt
index 025284dd46..cdf73915c4 100644
--- a/collects/planet2/lib.rkt
+++ b/collects/planet2/lib.rkt
@@ -211,8 +211,13 @@
 (define (package-index-lookup pkg)
   (or
    (for/or ([i (in-list (read-pkg-cfg/def "indexes"))])
-     (define addr (combine-url/relative (string->url i)
-                                        (format "pkg/~a" pkg)))
+     (define addr/no-query (combine-url/relative (string->url i)
+                                                 (format "pkg/~a" pkg)))
+     (define addr (struct-copy url addr/no-query
+                               [query (append
+                                       (url-query addr/no-query)
+                                       (list
+                                        (cons 'version (version))))]))
      (log-planet2-debug "resolving via ~a" (url->string addr))
      (call/input-url+200
       addr
diff --git a/collects/planet2/scribblings/planet2.scrbl b/collects/planet2/scribblings/planet2.scrbl
index 0397f64c2c..ebc6a8c192 100644
--- a/collects/planet2/scribblings/planet2.scrbl
+++ b/collects/planet2/scribblings/planet2.scrbl
@@ -154,11 +154,14 @@ means that it has only the characters @|package-name-chars|.}
 
 A @deftech{package name resolver} (@deftech{PNR}) is a server that
 converts package names to other package sources. A PNR is identified
-by a string representing a URL, such that appending
-@exec{pkg/}@nonterm{package} forms a URL that refers to a
+by a string representing a URL. This URL is combined with
+@exec{pkg/}@nonterm{package} path segments (where @nonterm{package} is a package name) plus a
+@exec{version=}@nonterm{version} query (where @nonterm{version} is the
+Racket version number) to form a URL that should refer to a
 @racket[read]-able hash table with the keys: @racket['source] mapped to
 the @tech{package source} string and @racket['checksum] mapped to the
-@tech{checksum} value. Typically, the source will be a remote URL.
+@tech{checksum} value. Typically, the @tech{package source} value for
+@racket['source] will be a remote URL.
 
 PLT supports two @tech{package name resolvers} that are enabled by
 default: @url{https://plt-etc.byu.edu:9004} for new