there seems to be an issue on windows where having an executable foo on the PATH and a folder foo in the cwd causes windows to be confused between the two. therefore, I renamed the folders for uncrustify and elm-format.

appveyor.yml

@@ -112,14 +112,14 @@ install:
   # Uncrustify
   - curl -k -L http://sourceforge.net/projects/uncrustify/files/uncrustify/uncrustify-0.61/uncrustify-0.61.3-gf65394e-win32.zip/download -o uncrustify.zip
   - cinst 7zip.commandline -y
-  - 7za e uncrustify.zip -ouncrustify
-  - "SET PATH=%cd%\\uncrustify;%PATH%"
+  - 7za e uncrustify.zip -ouncrustify-d
+  - "SET PATH=%cd%\\uncrustify-d;%PATH%"
   - where uncrustify
 
   # elm-format
   - curl -k -L https://github.com/avh4/elm-format/releases/download/0.2.0-alpha/elm-format-0.2.0-alpha-win-x64.zip -o elm-format.zip
-  - 7za e elm-format.zip -oelm-format
-  - "SET PATH=%cd%\\elm-format;%PATH%"
+  - 7za e elm-format.zip -oelm-format-d
+  - "SET PATH=%cd%\\elm-format-d;%PATH%"
   - where elm-format
 
 build_script:
@@ -129,7 +129,5 @@ build_script:
   - apm install language-marko language-html-swig language-svg language-elm language-d mavensmate-atom
   # Show current PATH
   - echo %PATH%
-  - where uncrustify
-  - where elm-format
   # Run tests on package
   - "%LOCALAPPDATA%\\atom\\bin\\atom.cmd --test spec"