diff --git a/src/main/groovy/com/google/protobuf/gradle/ToolsLocator.groovy b/src/main/groovy/com/google/protobuf/gradle/ToolsLocator.groovy
index 23c2a5db..b2a77288 100644
--- a/src/main/groovy/com/google/protobuf/gradle/ToolsLocator.groovy
+++ b/src/main/groovy/com/google/protobuf/gradle/ToolsLocator.groovy
@@ -100,6 +100,7 @@ class ToolsLocator {
     OsDetector osdetector = project.extensions.getByName("osdetector") as OsDetector
     List<String> parts = artifactParts(locator.artifact)
     (groupId, artifact, version, classifier, extension) = [parts[0], parts[1], parts[2], parts[3], parts[4]]
+    version = version ?: ''
     classifier = classifier ?: osdetector.classifier
     extension = extension ?: "exe"
     String notation = "$groupId:$artifact:$version:$classifier@${extension}"