zipping folder starting wit dot '.' results in two folders in zip file

[ilya-payrange]

jzip -o sourcemaps.zip .sourcemaps/
results in wrong content, file sourcemaps.zip has 2 directories in it, one with dot '.', another without:

 |- .sourcemaps
 |   |- (empty)
 |- sourcemaps
 |   |- file1.js.map
 |   |- file2.js.map
 |   |- ...

Windows 7 64-bit
node v8.11.2