diff --git a/changes/bug2077_share_delete b/changes/bug2077_share_delete
new file mode 100644
index 0000000000..71e9160538
--- /dev/null
+++ b/changes/bug2077_share_delete
@@ -0,0 +1,7 @@
+  o Major bugfixes (windows):
+    - Open files to be mapped with FILE_SHARE_DELETE so that we can
+      replace them before closing the mapping. This is a likely cause of
+      warnings and crashes when replacing the microdescriptor cache
+      file. Diagnosed based on comments by "doorss" and by Robert
+      Ransom. Possible fix for bug 2077; bugfix on 0.2.2.6-alpha.
+
diff --git a/src/common/compat.c b/src/common/compat.c
index c97a4545c9..cb1dd787a0 100644
--- a/src/common/compat.c
+++ b/src/common/compat.c
@@ -248,7 +248,7 @@ tor_mmap_file(const char *filename)
   strlcpy(tfilename,filename,MAX_PATH);
 #endif
   file_handle = CreateFile(tfilename,
-                           GENERIC_READ, FILE_SHARE_READ,
+                           GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_DELETE,
                            NULL,
                            OPEN_EXISTING,
                            FILE_ATTRIBUTE_NORMAL,
diff --git a/src/test/test_microdesc.c b/src/test/test_microdesc.c
index 4bc9fa7263..a8171a325c 100644
--- a/src/test/test_microdesc.c
+++ b/src/test/test_microdesc.c
@@ -208,11 +208,25 @@ test_md_cache(void *data)
   md3 = NULL; /* it's history now! */
 
   /* rebuild again, make sure it stays gone. */
-  microdesc_cache_rebuild(mc, 1);
+  tt_int_op(microdesc_cache_rebuild(mc, 1), ==, 0);
   tt_ptr_op(md1, ==, microdesc_cache_lookup_by_digest256(mc, d1));
   tt_ptr_op(md2, ==, microdesc_cache_lookup_by_digest256(mc, d2));
   tt_ptr_op(NULL, ==, microdesc_cache_lookup_by_digest256(mc, d3));
 
+  /* Re-add md3, and make sure we can rebuild the cache. */
+  added = microdescs_add_to_cache(mc, test_md3_noannotation, NULL,
+                                  SAVED_NOWHERE, 0, time3, NULL);
+  tt_int_op(1, ==, smartlist_len(added));
+  md3 = smartlist_get(added, 0);
+  smartlist_free(added);
+  added = NULL;
+  tt_int_op(md1->saved_location, ==, SAVED_IN_CACHE);
+  tt_int_op(md2->saved_location, ==, SAVED_IN_CACHE);
+  tt_int_op(md3->saved_location, ==, SAVED_IN_JOURNAL);
+
+  tt_int_op(microdesc_cache_rebuild(mc, 1), ==, 0);
+  tt_int_op(md3->saved_location, ==, SAVED_IN_CACHE);
+
  done:
   if (options)
     tor_free(options->DataDirectory);