diff --git a/src/zippy/tarballs_v1.nim b/src/zippy/tarballs_v1.nim
index 08926a0..ab8db43 100644
--- a/src/zippy/tarballs_v1.nim
+++ b/src/zippy/tarballs_v1.nim
@@ -46,10 +46,10 @@ proc addDir*(
   tarball: Tarball, dir: string
 ) {.raises: [IOError, OSError, ZippyError].} =
   ## Recursively adds all of the files and directories inside dir to tarball.
-  if splitFile(dir).ext.len > 0:
+  if not dirExists(dir):
     raise newException(
       ZippyError,
-      "Error adding dir " & dir & " to tarball, appears to be a file?"
+      "Error adding dir " & dir & " to tarball, not a directory?"
     )
 
   let (head, tail) = splitPath(dir)
diff --git a/src/zippy/ziparchives_v1.nim b/src/zippy/ziparchives_v1.nim
index 5780c74..a2c65cc 100644
--- a/src/zippy/ziparchives_v1.nim
+++ b/src/zippy/ziparchives_v1.nim
@@ -44,10 +44,10 @@ proc addDir*(
   archive: ZipArchive, dir: string
 ) {.raises: [IOError, OSError, ZippyError].} =
   ## Recursively adds all of the files and directories inside dir to archive.
-  if splitFile(dir).ext.len > 0:
+  if not dirExists(dir):
     raise newException(
       ZippyError,
-      "Error adding dir " & dir & " to archive, appears to be a file?"
+      "Error adding dir " & dir & " to archive, not a directory?"
     )
 
   let (head, tail) = splitPath(dir)
diff --git a/tests/all.nim b/tests/all.nim
index 5346be2..3862a9f 100644
--- a/tests/all.nim
+++ b/tests/all.nim
@@ -1 +1 @@
-import test, test_known_bad, test_levels, test_tarballs_read, test_ziparchives_read, test_ziparchives_write
+import test, test_known_bad, test_levels, test_tarballs_read, test_ziparchives_read, test_ziparchives_write, test_issue_97
diff --git a/tests/test_issue_97.nim b/tests/test_issue_97.nim
new file mode 100644
index 0000000..57aff03
--- /dev/null
+++ b/tests/test_issue_97.nim
@@ -0,0 +1,50 @@
+import std/os, std/strutils, zippy/tarballs, zippy/ziparchives
+
+# https://github.com/guzba/zippy/issues/97
+# A directory whose name contains a period (e.g. `/etc/cron.d`) must not be
+# mistaken for a file and rejected: addDir used the filename extension instead
+# of checking the filesystem.
+
+proc containsFile(dir, name, contents: string): bool =
+  for path in walkDirRec(dir):
+    if path.extractFilename == name and readFile(path) == contents:
+      return true
+  false
+
+block:
+  let dir = getTempDir() / "zippy_dotted.d"
+  removeDir(dir)
+  createDir(dir)
+  writeFile(dir / "a.txt", "hello")
+
+  # tarball
+  let tarPath = getTempDir() / "zippy_dotted.tar.gz"
+  createTarball(dir, tarPath) # must not raise
+  doAssert fileExists(tarPath)
+  let tarOut = getTempDir() / "zippy_dotted_tar_out"
+  removeDir(tarOut)
+  tarballs.extractAll(tarPath, tarOut)
+  doAssert containsFile(tarOut, "a.txt", "hello")
+
+  # zip
+  let zipPath = getTempDir() / "zippy_dotted.zip"
+  createZipArchive(dir, zipPath) # must not raise
+  doAssert fileExists(zipPath)
+  let zipOut = getTempDir() / "zippy_dotted_zip_out"
+  removeDir(zipOut)
+  ziparchives.extractAll(zipPath, zipOut)
+  doAssert containsFile(zipOut, "a.txt", "hello")
+
+  removeDir(dir)
+  removeFile(tarPath)
+  removeFile(zipPath)
+  removeDir(tarOut)
+  removeDir(zipOut)
+
+# A real file (or a nonexistent path) is still rejected.
+block:
+  let file = getTempDir() / "zippy_not_a_dir.txt"
+  writeFile(file, "x")
+  doAssertRaises ZippyError:
+    createTarball(file, getTempDir() / "zippy_not_a_dir.tar.gz")
+  removeFile(file)