diff --git a/misc/build_helpers/run-deprecations.py b/misc/build_helpers/run-deprecations.py
index 6c76bcd69..3972d5c89 100644
--- a/misc/build_helpers/run-deprecations.py
+++ b/misc/build_helpers/run-deprecations.py
@@ -1,6 +1,6 @@
 from __future__ import print_function
 
-import sys, os, io
+import sys, os, io, re
 from twisted.internet import reactor, protocol, task, defer
 from twisted.python.procutils import which
 from twisted.python import usage
@@ -12,6 +12,7 @@ from twisted.python import usage
 class Options(usage.Options):
     optParameters = [
         ["warnings", None, None, "file to write warnings into at end of test run"],
+        ["package", None, None, "Python package to which to restrict warning collection"]
         ]
 
     def parseArgs(self, command, *args):
@@ -19,7 +20,7 @@ class Options(usage.Options):
         self["args"] = list(args)
 
     description = """Run as:
-PYTHONWARNINGS=default::DeprecationWarning python run-deprecations.py [--warnings=STDERRFILE]  COMMAND ARGS..
+PYTHONWARNINGS=default::DeprecationWarning python run-deprecations.py [--warnings=STDERRFILE] [--package=PYTHONPACKAGE ] COMMAND ARGS..
 """
 
 class RunPP(protocol.ProcessProtocol):
@@ -34,6 +35,34 @@ class RunPP(protocol.ProcessProtocol):
         rc = reason.value.exitCode
         self.d.callback((signal, rc))
 
+
+def make_matcher(options):
+    """
+    Make a function that matches a line with a relevant deprecation.
+
+    A deprecation warning line looks something like this::
+
+      somepath/foo/bar/baz.py:43: DeprecationWarning: Foo is deprecated, try bar instead.
+
+    Sadly there is no guarantee warnings begin at the beginning of a line
+    since they are written to output without coordination with whatever other
+    Python code is running in the process.
+
+    :return: A one-argument callable that accepts a string and returns
+        ``True`` if it contains an interesting warning and ``False``
+        otherwise.
+    """
+    pattern = r".*\.py[oc]?:\d+:" # (Pending)?DeprecationWarning: .*"
+    if options["package"]:
+        pattern = r".*/{}/".format(
+            re.escape(options["package"]),
+        ) + pattern
+    expression = re.compile(pattern)
+    def match(line):
+        return expression.match(line) is not None
+    return match
+
+
 @defer.inlineCallbacks
 def run_command(main):
     config = Options()
@@ -63,6 +92,8 @@ def run_command(main):
     reactor.spawnProcess(pp, exe, [exe] + config["args"], env=None)
     (signal, rc) = yield pp.d
 
+    match = make_matcher(config)
+
     # maintain ordering, but ignore duplicates (for some reason, either the
     # 'warnings' module or twisted.python.deprecate isn't quashing them)
     already = set()
@@ -75,12 +106,12 @@ def run_command(main):
 
     pp.stdout.seek(0)
     for line in pp.stdout.readlines():
-        if "DeprecationWarning" in line:
+        if match(line):
             add(line) # includes newline
 
     pp.stderr.seek(0)
     for line in pp.stderr.readlines():
-        if "DeprecationWarning" in line:
+        if match(line):
             add(line)
 
     if warnings:
diff --git a/newsfragments/3232.minor b/newsfragments/3232.minor
new file mode 100644
index 000000000..e69de29bb
diff --git a/tox.ini b/tox.ini
index 6164edd5e..e165ed168 100644
--- a/tox.ini
+++ b/tox.ini
@@ -97,7 +97,7 @@ commands =
 setenv =
          PYTHONWARNINGS=default::DeprecationWarning
 commands =
-         python misc/build_helpers/run-deprecations.py --warnings={env:TAHOE_LAFS_WARNINGS_LOG:_trial_temp/deprecation-warnings.log} trial {env:TAHOE_LAFS_TRIAL_ARGS:--rterrors} {posargs:allmydata}
+         python misc/build_helpers/run-deprecations.py --package allmydata --warnings={env:TAHOE_LAFS_WARNINGS_LOG:_trial_temp/deprecation-warnings.log} trial {env:TAHOE_LAFS_TRIAL_ARGS:--rterrors} {posargs:allmydata}
 
 [testenv:upcoming-deprecations]
 setenv =
@@ -109,7 +109,7 @@ deps =
      git+https://github.com/warner/foolscap
 commands =
          flogtool --version
-         python misc/build_helpers/run-deprecations.py --warnings={env:TAHOE_LAFS_WARNINGS_LOG:_trial_temp/deprecation-warnings.log} trial {env:TAHOE_LAFS_TRIAL_ARGS:--rterrors} {posargs:allmydata}
+         python misc/build_helpers/run-deprecations.py --package allmydata --warnings={env:TAHOE_LAFS_WARNINGS_LOG:_trial_temp/deprecation-warnings.log} trial {env:TAHOE_LAFS_TRIAL_ARGS:--rterrors} {posargs:allmydata}
 
 [testenv:checkmemory]
 commands =