diff --git a/base/src/proguard/KeepClassSpecification.java b/base/src/proguard/KeepClassSpecification.java
index d054571a..5a6fea02 100644
--- a/base/src/proguard/KeepClassSpecification.java
+++ b/base/src/proguard/KeepClassSpecification.java
@@ -84,6 +84,49 @@ public class KeepClassSpecification extends ClassSpecification
     }
 
 
+    /**
+     * Creates a new KeepClassSpecification.
+     *
+     * @param markClassesAndMembers specifies whether to mark the classes.
+     * @param markConditionally     specifies whether to mark the classes and
+     *                              class members conditionally. If true,
+     *                              classes and class members are marked, on
+     *                              the condition that all specified class
+     *                              members are present.
+     * @param markDescriptorClasses specifies whether to mark the classes in
+     *                              the descriptors of the marked class members.
+     * @param markCodeAttributes    specified whether to mark the code attributes
+     *                              of the marked class methods.
+     * @param allowShrinking        specifies whether shrinking is allowed.
+     * @param allowOptimization     specifies whether optimization is allowed.
+     * @param allowObfuscation      specifies whether obfuscation is allowed.
+     * @param condition             an optional extra condition.
+     * @param classSpecification    the specification of classes and class
+     *                              members.
+     */
+    @Deprecated
+    public KeepClassSpecification(boolean            markClassesAndMembers,
+                                  boolean            markConditionally,
+                                  boolean            markDescriptorClasses,
+                                  boolean            markCodeAttributes,
+                                  boolean            allowShrinking,
+                                  boolean            allowOptimization,
+                                  boolean            allowObfuscation,
+                                  ClassSpecification condition,
+                                  ClassSpecification classSpecification)
+    {
+        this(markClassesAndMembers,
+             markClassesAndMembers,
+             markConditionally,
+             markDescriptorClasses,
+             markCodeAttributes,
+             allowShrinking,
+             allowOptimization,
+             allowObfuscation,
+             condition,
+             classSpecification);
+    }
+
     // Implementations for Object.
 
     @Override
diff --git a/gradle-plugin/src/test/kotlin/proguard/gradle/ProGuardPluginLegacyAGPIntegrationTest.kt b/gradle-plugin/src/test/kotlin/proguard/gradle/ProGuardPluginLegacyAGPIntegrationTest.kt
index 4973913e..e8c762a1 100644
--- a/gradle-plugin/src/test/kotlin/proguard/gradle/ProGuardPluginLegacyAGPIntegrationTest.kt
+++ b/gradle-plugin/src/test/kotlin/proguard/gradle/ProGuardPluginLegacyAGPIntegrationTest.kt
@@ -15,6 +15,7 @@ import testutils.AndroidProject
 import testutils.applicationModule
 import testutils.createGradleRunner
 import testutils.createTestKitDir
+import testutils.libraryModule
 
 class ProGuardPluginLegacyAGPIntegrationTest : FreeSpec({
     val testKitDir = createTestKitDir()
@@ -81,4 +82,77 @@ class ProGuardPluginLegacyAGPIntegrationTest : FreeSpec({
             }
         }
     }
+
+    "Given a library project with the legacy integration" - {
+        val project = autoClose(AndroidProject(
+                gradleDotProperties = """
+                    |android.enableR8=false
+                    |android.enableR8.libraries=false
+                    |android.useAndroidX=true
+                """.trimMargin(), buildDotGradle = """
+            buildscript {
+                repositories {
+                    mavenCentral() // For anything else.
+                    google()       // For the Android plugin.
+                    flatDir {
+                        dirs "${System.getProperty("local.repo")}"
+                    }
+                }
+                dependencies {
+                    classpath "com.android.tools.build:gradle:4.2.0"
+                    classpath ":proguard-gradle:${System.getProperty("proguard.version")}"
+                }
+
+                configurations.all {
+                    resolutionStrategy {
+                        dependencySubstitution {
+                            substitute module('net.sf.proguard:proguard-gradle') with module("com.guardsquare:proguard-gradle:${System.getProperty("proguard.version")}")
+                        }
+                    }
+                }
+            }
+            allprojects {
+                repositories {
+                    google()
+                    mavenCentral()
+                }
+            }
+            """.trimIndent()).apply {
+                addModule(libraryModule(
+                        "library",
+                        buildDotGradle = """
+                            plugins {
+                                id 'com.android.library'
+                            }
+
+                            dependencies {
+                                implementation 'androidx.appcompat:appcompat:1.2.0'
+                            }
+
+                            android {
+                                compileSdkVersion 29
+                                defaultConfig {
+                                    targetSdkVersion 29
+                                    minSdkVersion 14
+                                }
+                                buildTypes {
+                                    release {
+                                        minifyEnabled true
+                                        proguardFile getDefaultProguardFile('proguard-android.txt')
+                                    }
+                                    debug {}
+                                }
+                            }
+                        """))
+            }.create())
+
+        "When the project is evaluated" - {
+            val result = createGradleRunner(project.rootDir, testKitDir, "clean", "assembleRelease", "--info").build()
+
+            "Then the build should success" {
+                result.output shouldContain "ProGuard, version ${System.getProperty("proguard.version")}"
+                result.task(":library:assembleRelease")?.outcome shouldBe TaskOutcome.SUCCESS
+            }
+        }
+    }
 })