diff --git a/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/reporter/PlainTextReporter.kt b/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/reporter/PlainTextReporter.kt
index a938c804..b52f470b 100644
--- a/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/reporter/PlainTextReporter.kt
+++ b/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/reporter/PlainTextReporter.kt
@@ -191,7 +191,7 @@ class PlainTextReporter(
   companion object {
     /** Returns the dependency key as a stringified label. */
     private fun label(dependency: Dependency): String {
-      return "${dependency.group}:${dependency.name}"
+      return "${dependency.group.orEmpty()}:${dependency.name}"
     }
   }
 }
diff --git a/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/updates/Resolver.kt b/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/updates/Resolver.kt
index f661a088..1c36cc42 100644
--- a/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/updates/Resolver.kt
+++ b/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/updates/Resolver.kt
@@ -69,7 +69,7 @@ class Resolver(
       val resolvedCoordinate = Coordinate.from(dependency.module.id)
       val originalCoordinate = coordinates[resolvedCoordinate.key]
       val coord = originalCoordinate ?: resolvedCoordinate
-      if (originalCoordinate == null && resolvedCoordinate.groupId != "null") {
+      if (originalCoordinate == null && resolvedCoordinate.groupId != "none") {
         project.logger.info("Skipping hidden dependency: $resolvedCoordinate")
       } else {
         val projectUrl = getProjectUrl(dependency.module.id)
@@ -167,7 +167,7 @@ class Resolver(
     }
 
     // Format the query with an optional classifier and extension
-    var query = "${dependency.group}:${dependency.name}:$version"
+    var query = "${dependency.group.orEmpty()}:${dependency.name}:$version"
     if (dependency.artifacts.isNotEmpty()) {
       dependency.artifacts.firstOrNull()?.classifier?.let { classifier ->
         query += ":$classifier"
@@ -191,7 +191,7 @@ class Resolver(
     // If no version was specified then use "none" to pass it through.
     val version = if (dependency.version == null) "none" else "+"
     val nonTransitiveDependency =
-      project.dependencies.create("${dependency.group}:${dependency.name}:$version") as ModuleDependency
+      project.dependencies.create("${dependency.group.orEmpty()}:${dependency.name}:$version") as ModuleDependency
     nonTransitiveDependency.isTransitive = false
     return nonTransitiveDependency
   }
@@ -249,7 +249,7 @@ class Resolver(
   /** Returns the coordinates for the current (declared) dependency versions. */
   private fun getCurrentCoordinates(configuration: Configuration): Map<Coordinate.Key, Coordinate> {
     val declared = getResolvableDependencies(configuration)
-      .associateBy({ it.key }, { it })
+      .associateBy { it.key }
     if (declared.isEmpty()) {
       return emptyMap()
     }
@@ -378,7 +378,7 @@ class Resolver(
             } else {
               val parent = getParentFromPom(file)
               if (parent != null &&
-                "${parent.group}:${parent.name}" != "org.sonatype.oss:oss-parent"
+                "${parent.group.orEmpty()}:${parent.name}" != "org.sonatype.oss:oss-parent"
               ) {
                 url = getProjectUrl(parent)
                 if (!url.isNullOrEmpty()) {
diff --git a/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/updates/resolutionstrategy/ComponentSelectionWithCurrent.kt b/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/updates/resolutionstrategy/ComponentSelectionWithCurrent.kt
index 65c719d4..4eb1bef7 100644
--- a/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/updates/resolutionstrategy/ComponentSelectionWithCurrent.kt
+++ b/gradle-versions-plugin/src/main/kotlin/com/github/benmanes/gradle/versions/updates/resolutionstrategy/ComponentSelectionWithCurrent.kt
@@ -10,7 +10,7 @@ class ComponentSelectionWithCurrent(
   override fun toString(): String {
     return """\
 ComponentSelectionWithCurrent{
-    group="${candidate.group}",
+    group="${candidate.group.orEmpty()}",
     module="${candidate.module}",
     version="${candidate.version}",
     currentVersion="$currentVersion",
diff --git a/gradle-versions-plugin/src/test/groovy/com/github/benmanes/gradle/versions/DependencyUpdatesSpec.groovy b/gradle-versions-plugin/src/test/groovy/com/github/benmanes/gradle/versions/DependencyUpdatesSpec.groovy
index 0bb69437..12a76ce9 100644
--- a/gradle-versions-plugin/src/test/groovy/com/github/benmanes/gradle/versions/DependencyUpdatesSpec.groovy
+++ b/gradle-versions-plugin/src/test/groovy/com/github/benmanes/gradle/versions/DependencyUpdatesSpec.groovy
@@ -358,11 +358,11 @@ final class DependencyUpdatesSpec extends Specification {
     with(reporter) {
       unresolved.collect { it.selector }.collectEntries { dependency ->
         [['group': dependency.group, 'name': dependency.name]: dependency.version]
-      } == [['group': 'null', 'name': 'guava-18.0']: NONE_VERSION]
+      } == [['group': '', 'name': 'guava-18.0']: NONE_VERSION]
       upgradeVersions.isEmpty()
       upToDateVersions.isEmpty()
       downgradeVersions.isEmpty()
-      undeclared.contains(new Coordinate('null', 'guice-4.0', NONE_VERSION, null))
+      undeclared.contains(new Coordinate('', 'guice-4.0', NONE_VERSION, null))
     }
   }