diff --git a/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowJavaPlugin.kt b/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowJavaPlugin.kt
index ff017e8ca..bf69e3059 100644
--- a/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowJavaPlugin.kt
+++ b/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowJavaPlugin.kt
@@ -7,6 +7,7 @@ import com.github.jengelman.gradle.plugins.shadow.internal.runtimeConfiguration
 import com.github.jengelman.gradle.plugins.shadow.internal.sourceSets
 import com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar.Companion.registerShadowJarCommon
 import com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar.Companion.shadowJar
+import java.io.File
 import javax.inject.Inject
 import org.gradle.api.NamedDomainObjectProvider
 import org.gradle.api.Plugin
@@ -42,6 +43,11 @@ constructor(private val softwareComponentFactory: SoftwareComponentFactory) : Pl
       registerShadowJarCommon(tasks.named("jar", Jar::class.java)) { task ->
         task.from(sourceSets.named("main").map { it.output })
         task.configurations.convention(provider { listOf(runtimeConfiguration) })
+        // Include all source sets (including test) so that test code's transitive dependency
+        // references are also considered "used" during minimization.
+        task.sourceSetsClassesDirs.convention(
+          sourceSets.map { it.output.classesDirs.filter(File::isDirectory) }
+        )
       }
     artifacts.add(configurations.shadow.name, taskProvider)
   }
diff --git a/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowKmpPlugin.kt b/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowKmpPlugin.kt
index c8bb3a257..2fe756555 100644
--- a/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowKmpPlugin.kt
+++ b/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowKmpPlugin.kt
@@ -3,6 +3,7 @@ package com.github.jengelman.gradle.plugins.shadow
 import com.github.jengelman.gradle.plugins.shadow.internal.isAtLeastKgp
 import com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar.Companion.SHADOW_JAR_TASK_NAME
 import com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar.Companion.registerShadowJarCommon
+import java.io.File
 import org.gradle.api.Plugin
 import org.gradle.api.Project
 import org.gradle.api.tasks.bundling.Jar
@@ -41,6 +42,13 @@ public abstract class ShadowKmpPlugin : Plugin<Project> {
           .flatMap { configurations.named(it.runtimeDependencyConfigurationName) }
           .map { listOf(it) }
       )
+      // Include all compilations (including test) so that test code's transitive dependency
+      // references are also considered "used" during minimization.
+      task.sourceSetsClassesDirs.convention(
+        target.compilations.map { compilation ->
+          compilation.output.classesDirs.filter(File::isDirectory)
+        }
+      )
 
       if (!isAtLeastKgp("1.9.0")) return@registerShadowJarCommon
 
diff --git a/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/tasks/ShadowJar.kt b/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/tasks/ShadowJar.kt
index 23020620d..cc020c98a 100644
--- a/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/tasks/ShadowJar.kt
+++ b/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/tasks/ShadowJar.kt
@@ -20,7 +20,6 @@ import com.github.jengelman.gradle.plugins.shadow.internal.minimizeWithR8
 import com.github.jengelman.gradle.plugins.shadow.internal.multiReleaseAttributeKey
 import com.github.jengelman.gradle.plugins.shadow.internal.property
 import com.github.jengelman.gradle.plugins.shadow.internal.setProperty
-import com.github.jengelman.gradle.plugins.shadow.internal.sourceSets
 import com.github.jengelman.gradle.plugins.shadow.internal.useZip
 import com.github.jengelman.gradle.plugins.shadow.relocation.CacheableRelocator
 import com.github.jengelman.gradle.plugins.shadow.relocation.Relocator
@@ -138,17 +137,7 @@ public abstract class ShadowJar : Jar() {
 
   @get:InputFiles
   @get:PathSensitive(PathSensitivity.RELATIVE)
-  public open val sourceSetsClassesDirs: ConfigurableFileCollection = objectFactory.fileCollection {
-    _minimizeJar.map {
-      if (it) {
-        project.sourceSets.map { sourceSet ->
-          sourceSet.output.classesDirs.filter(File::isDirectory)
-        }
-      } else {
-        emptySet()
-      }
-    }
-  }
+  public open val sourceSetsClassesDirs: ConfigurableFileCollection = objectFactory.fileCollection()
 
   @get:Classpath
   public open val r8Classpath: ConfigurableFileCollection = objectFactory.fileCollection {