diff --git a/maven-plugin/src/main/java/com/sourcegraph/maven/DependencyWriterMojo.java b/maven-plugin/src/main/java/com/sourcegraph/maven/DependencyWriterMojo.java
index c8b3d918..fdab05d8 100644
--- a/maven-plugin/src/main/java/com/sourcegraph/maven/DependencyWriterMojo.java
+++ b/maven-plugin/src/main/java/com/sourcegraph/maven/DependencyWriterMojo.java
@@ -97,6 +97,6 @@ public void execute() throws MojoExecutionException, MojoFailureException {
 
   private String summariseArtifact(Artifact artifact) {
     return String.format(
-        "%:%:%", artifact.getGroupId(), artifact.getArtifactId(), artifact.getVersion());
+        "%s:%s:%s", artifact.getGroupId(), artifact.getArtifactId(), artifact.getVersion());
   }
 }