diff --git a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/maven/aether/Filters.kt b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/maven/aether/Filters.kt
index 6af9cb27..d4409b03 100644
--- a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/maven/aether/Filters.kt
+++ b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/maven/aether/Filters.kt
@@ -1,6 +1,8 @@
 package com.beust.kobalt.maven.aether
 
+import com.beust.kobalt.misc.kobaltLog
 import org.eclipse.aether.graph.DependencyFilter
+import org.eclipse.aether.graph.DependencyNode
 import org.eclipse.aether.util.artifact.JavaScopes
 
 object Filters {
@@ -9,7 +11,15 @@ object Filters {
     }
     val TEST_FILTER = DependencyFilter { p0, p1 -> p0.dependency.scope == JavaScopes.TEST }
 
-    val EXCLUDE_OPTIONAL_FILTER = DependencyFilter { p0, p1 ->
-        p0.dependency != null && ! p0.dependency.optional
+    val EXCLUDE_OPTIONAL_FILTER = object: DependencyFilter {
+        override fun accept(p0: DependencyNode, p1: MutableList<DependencyNode>): Boolean {
+            val result = p0.dependency != null && ! p0.dependency.optional
+            if (! result) {
+                kobaltLog(2, "Excluding from optional filter: $p0")
+            }
+            return result
+        }
+
+        override fun toString() = "EXCLUDE_OPTIONAL_FILTER"
     }
 }