diff --git a/.circleci/config.yml b/.circleci/config.yml
index f662a3702..1327a524b 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -154,6 +154,8 @@ jobs:
       # we maintain.
       WHEELHOUSE_PATH: &WHEELHOUSE_PATH "/tmp/wheelhouse"
       PIP_FIND_LINKS: "file:///tmp/wheelhouse"
+      # Upload the coverage report.
+      UPLOAD_COVERAGE: "yes"
 
     # pip cannot install packages if the working directory is not readable.
     # We want to run a lot of steps as nobody instead of as root.
@@ -202,7 +204,9 @@ jobs:
       - run: &SUBMIT_COVERAGE
           name: "Submit coverage results"
           command: |
-            /tmp/venv/bin/codecov
+            if [ -n "${UPLOAD_COVERAGE}" ]; then
+              /tmp/venv/bin/codecov
+            fi
 
 
   debian-8:
@@ -222,6 +226,8 @@ jobs:
       <<: *UTF_8_ENVIRONMENT
       # We don't do coverage since it makes PyPy far too slow:
       TAHOE_LAFS_TOX_ENVIRONMENT: "pypy27"
+      # Since we didn't collect it, don't upload it.
+      UPLOAD_COVERAGE: ""
 
 
   c-locale:
@@ -250,6 +256,8 @@ jobs:
       TAHOE_LAFS_TOX_ENVIRONMENT: "deprecations,upcoming-deprecations"
       # Put the logs somewhere we can report them.
       TAHOE_LAFS_WARNINGS_LOG: "/tmp/artifacts/deprecation-warnings.log"
+      # The deprecations tox environments don't do coverage measurement.
+      UPLOAD_COVERAGE: ""
 
 
   integration:
diff --git a/.coveragerc b/.coveragerc
index 636258717..d09554cad 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -14,3 +14,14 @@ branch = True
 [report]
 show_missing = True
 skip_covered = True
+
+[paths]
+source =
+# It looks like this in the checkout
+    src/
+# It looks like this in the Windows build environment
+    D:/a/tahoe-lafs/tahoe-lafs/.tox/py*-coverage/Lib/site-packages/
+# Although sometimes it looks like this instead.  Also it looks like this on macOS.
+    .tox/py*-coverage/lib/python*/site-packages/
+# On some Linux CI jobs it looks like this
+    /tmp/tahoe-lafs.tox/py*-coverage/lib/python*/site-packages/
diff --git a/newsfragments/3472.minor b/newsfragments/3472.minor
new file mode 100644
index 000000000..e69de29bb