diff --git a/appveyor.yml b/appveyor.yml
index af1f130bb..e1b893c9a 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -6,7 +6,7 @@ branches:
 
 environment:
   STACK_ROOT: C:\sr
-  STACK_VERSION: 1.9.3
+  STACK_VERSION: 2.1.1
 
   # Workaround a gnarly bug https://github.com/haskell/cabal/issues/5386
   # See: https://www.fpcomplete.com/blog/2018/06/sed-a-debugging-story
diff --git a/stack.yaml b/stack.yaml
index 8c9df5e01..8f4d1ed25 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -22,5 +22,7 @@ extra-deps:
 - semver-range-0.2.8
 - directory-1.3.4.0@sha256:500019f04494324d1df16cf83eefeb3f809b2b20b32a32ccd755ee0439c18bfd
 - process-1.6.5.1@sha256:77a9afeb676357f67fe5cf1ad79aca0745fb6f7fb96b786d510af08f622643f6,2468
+- time-1.8.0.4@sha256:3f6eddf238b828eb4f82683acce1c3afe64784f0d20114239b738c123316c85c,5494
+- unix-2.7.2.2@sha256:e69269a17b9fa26cb77f3f55e86c39d0a4940ccfa0c4bc20826919d2572076ad,3496
 nix:
   packages: [zlib]
diff --git a/stack.yaml.lock b/stack.yaml.lock
index 44dced307..cf2a4e5f1 100644
--- a/stack.yaml.lock
+++ b/stack.yaml.lock
@@ -130,6 +130,34 @@ packages:
       sha256: fd72964da8246cc09d477b4c6e6f20971de058917d08d9f8183f5c0e2116f9c6
   original:
     hackage: semver-range-0.2.8
+- completed:
+    hackage: directory-1.3.4.0@sha256:500019f04494324d1df16cf83eefeb3f809b2b20b32a32ccd755ee0439c18bfd,2829
+    pantry-tree:
+      size: 3365
+      sha256: 00c09e0c014d29ebfb921b64c1459e61a0ad6f10e70128d795246a47c06394b0
+  original:
+    hackage: directory-1.3.4.0@sha256:500019f04494324d1df16cf83eefeb3f809b2b20b32a32ccd755ee0439c18bfd
+- completed:
+    hackage: process-1.6.5.1@sha256:77a9afeb676357f67fe5cf1ad79aca0745fb6f7fb96b786d510af08f622643f6,2468
+    pantry-tree:
+      size: 1211
+      sha256: 19d944da6aa37944332e0726372288319852e5f72aa57dbc3516dc15e760a502
+  original:
+    hackage: process-1.6.5.1@sha256:77a9afeb676357f67fe5cf1ad79aca0745fb6f7fb96b786d510af08f622643f6,2468
+- completed:
+    hackage: time-1.8.0.4@sha256:3f6eddf238b828eb4f82683acce1c3afe64784f0d20114239b738c123316c85c,5494
+    pantry-tree:
+      size: 5406
+      sha256: 1a186b21ff55d3e8f7d66ed2075bbce4dcc9ccaeef87665aa88752412f14073f
+  original:
+    hackage: time-1.8.0.4@sha256:3f6eddf238b828eb4f82683acce1c3afe64784f0d20114239b738c123316c85c,5494
+- completed:
+    hackage: unix-2.7.2.2@sha256:e69269a17b9fa26cb77f3f55e86c39d0a4940ccfa0c4bc20826919d2572076ad,3496
+    pantry-tree:
+      size: 3536
+      sha256: c355f7924ce67e5bf8f20767462af18f09b8c0d1f7161117221cbb94c15deee3
+  original:
+    hackage: unix-2.7.2.2@sha256:e69269a17b9fa26cb77f3f55e86c39d0a4940ccfa0c4bc20826919d2572076ad,3496
 snapshots:
 - completed:
     size: 508406