diff --git a/packaging/windows/install.ps1 b/packaging/windows/install.ps1
index 714851fdc..044c3af2d 100644
--- a/packaging/windows/install.ps1
+++ b/packaging/windows/install.ps1
@@ -3,12 +3,12 @@ C:\Python27\python.exe setup.py install
 # If this is a build because of a tag, make sure that
 # its either a testing tag or a tag that matches the version
 # specified in the source code.
-If ($(APPVEYOR_REPO_TAG) -Match "true") {
-   If ($(APPVEYOR_REPO_TAG_NAME) -Like "test*") {
+If (${Env:APPVEYOR_REPO_TAG} -Match "true") {
+   If (${Env:APPVEYOR_REPO_TAG_NAME} -Like "test*") {
       exit 0
    }
    # non-testing tags should be in the form v1.2.3
-   If ("v$(C:\Python27\python.exe setup.py -V)" -Match $(APPVEYOR_REPO_TAG_NAME)) {
+   If ("v$(C:\Python27\python.exe setup.py -V)" -Match ${Env:APPVEYOR_REPO_TAG_NAME}) {
       exit 0
    }
    exit 1