diff --git a/src/main/groovy/com/moowork/gradle/node/variant/VariantBuilder.groovy b/src/main/groovy/com/moowork/gradle/node/variant/VariantBuilder.groovy
index ba074d6..4dd9edb 100644
--- a/src/main/groovy/com/moowork/gradle/node/variant/VariantBuilder.groovy
+++ b/src/main/groovy/com/moowork/gradle/node/variant/VariantBuilder.groovy
@@ -29,7 +29,7 @@ class VariantBuilder
         variant.windows = platformHelper.isWindows()
 
         variant.nodeDir = getNodeDir( osName, osArch )
-        variant.npmDir = ext.npmVersion ? getNpmDir() : variant.nodeDir
+        variant.npmDir = this.ext.npmVersion ? getNpmDir() : variant.nodeDir
         variant.yarnDir = getYarnDir()
 
         variant.nodeBinDir = variant.nodeDir