diff --git a/chiasma-test.cabal b/chiasma-test.cabal
--- a/chiasma-test.cabal
+++ b/chiasma-test.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           chiasma-test
-version:        0.12.0.0
+version:        0.12.1.0
 synopsis:       Testing tools for chiasma
 description:    See https://hackage.haskell.org/package/chiasma-test/docs/Chiasma-Test.html
 category:       Terminal
@@ -104,6 +104,7 @@
       Chiasma.Test.LensTest
       Chiasma.Test.OutputParseTest
       Chiasma.Test.PinTest
+      Chiasma.Test.ProcessOutputTest
       Chiasma.Test.PureTest
       Chiasma.Test.Util
   hs-source-dirs:
@@ -153,6 +154,7 @@
     , lens >=4
     , polysemy
     , polysemy-plugin
+    , polysemy-process
     , polysemy-test >=0.6
     , prelate ==0.9.*
     , tasty
diff --git a/test/Chiasma/Test/ProcessOutputTest.hs b/test/Chiasma/Test/ProcessOutputTest.hs
new file mode 100644
--- /dev/null
+++ b/test/Chiasma/Test/ProcessOutputTest.hs
@@ -0,0 +1,61 @@
+module Chiasma.Test.ProcessOutputTest where
+
+import qualified Data.ByteString as ByteString
+import Hedgehog ((===))
+import Polysemy.Process.Effect.ProcessOutput (OutputPipe (Stdout), ProcessOutput (Chunk))
+
+import qualified Chiasma.Data.TmuxEvent as TmuxEvent
+import Chiasma.Data.TmuxNotification (TmuxNotification (..))
+import Chiasma.Data.TmuxOutputBlock (TmuxOutputBlock (..))
+import Chiasma.Interpreter.ProcessOutput (interpretProcessOutputTmuxEvent)
+import Chiasma.Test.Util (UnitTest)
+
+-- | Simulate a 'Chunk' call via the interpreter, returning parsed events.
+runChunk ::
+  ByteString ->
+  ByteString ->
+  IO ([Either Text TmuxEvent.TmuxEvent], ByteString)
+runChunk buffer new =
+  runM $
+  interpretProcessOutputTmuxEvent @'Stdout do
+    send (Chunk buffer new)
+
+-- | Two notifications concatenated in a single chunk.
+-- The bug causes only the first to be parsed, the second is lost.
+test_multiNotificationChunk :: UnitTest
+test_multiNotificationChunk = do
+  let
+    chunk = ByteString.intercalate "" [
+      "%window-add @1\n",
+      "%session-changed $0 main\n"
+      ]
+  (events, _leftover) <- liftIO (runChunk "" chunk)
+  [Right (TmuxEvent.Notification (TmuxNotification "window-add" ["@1"])),
+   Right (TmuxEvent.Notification (TmuxNotification "session-changed" ["$0", "main"]))]
+    === events
+
+-- | A response block followed by a notification in one chunk.
+test_responseAndNotificationChunk :: UnitTest
+test_responseAndNotificationChunk = do
+  let
+    chunk = ByteString.intercalate "" [
+      "%begin 123\n",
+      "some data\n",
+      "%end 123\n",
+      "%window-add @5\n"
+      ]
+  (events, _leftover) <- liftIO (runChunk "" chunk)
+  [Right (TmuxEvent.Response (Success ["some data"])),
+   Right (TmuxEvent.Notification (TmuxNotification "window-add" ["@5"]))]
+    === events
+
+-- | Leftovers from a previous chunk are passed as the buffer argument.
+-- The bug causes the buffer to be discarded.
+test_bufferContinuation :: UnitTest
+test_bufferContinuation = do
+  let
+    buffer = "%window-add"
+    new = " @3\n"
+  (events, _leftover) <- liftIO (runChunk buffer new)
+  [Right (TmuxEvent.Notification (TmuxNotification "window-add" ["@3"]))]
+    === events
diff --git a/test/Main.hs b/test/Main.hs
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -4,6 +4,8 @@
 import Chiasma.Test.LensTest (test_lenses)
 import Chiasma.Test.OutputParseTest (test_outputParse)
 import Chiasma.Test.PinTest (test_pin)
+import Chiasma.Test.ProcessOutputTest (test_bufferContinuation, test_multiNotificationChunk,
+  test_responseAndNotificationChunk)
 import Chiasma.Test.Util (unitTest)
 import Test.Tasty (TestTree, defaultMain, testGroup)
 
@@ -14,7 +16,10 @@
     unitTest "tmux-encode a query" test_query,
     test_lenses,
     unitTest "parse tmux output" test_outputParse,
-    test_pin
+    test_pin,
+    unitTest "multiple notifications in one chunk" test_multiNotificationChunk,
+    unitTest "response and notification in one chunk" test_responseAndNotificationChunk,
+    unitTest "buffer continuation across chunks" test_bufferContinuation
   ]
 
 main :: IO ()