diff --git a/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/main/kotlin/dev/sigstore/sign/SigstoreSignExtension.kt b/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/main/kotlin/dev/sigstore/sign/SigstoreSignExtension.kt
index 22fd84b7..e2fb43fc 100644
--- a/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/main/kotlin/dev/sigstore/sign/SigstoreSignExtension.kt
+++ b/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/main/kotlin/dev/sigstore/sign/SigstoreSignExtension.kt
@@ -84,7 +84,7 @@ abstract class SigstoreSignExtension(private val project: Project) {
         }
 
         val removeSigstoreAsc =
-            project.findProperty("dev.sigstore.sign.remove.sigstore.json.asc")?.toString()?.toBoolean() != false
+            project.providers.gradleProperty("dev.sigstore.sign.remove.sigstore.json.asc").orNull?.toBoolean() != false
 
         val publicationName = publication.name
 
diff --git a/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/test/kotlin/dev/sigstore/gradle/OidcDslTest.kt b/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/test/kotlin/dev/sigstore/gradle/OidcDslTest.kt
index 0a183c3c..0567fd4c 100644
--- a/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/test/kotlin/dev/sigstore/gradle/OidcDslTest.kt
+++ b/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/test/kotlin/dev/sigstore/gradle/OidcDslTest.kt
@@ -46,6 +46,7 @@ class OidcDslTest: BaseGradleTest() {
             """.trimIndent()
         )
         enableConfigurationCache(gradle)
+        enableProjectIsolation(gradle)
         prepare(gradle.version, "printConfig", "-s")
             .build()
     }
diff --git a/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/test/kotlin/dev/sigstore/gradle/SigstoreSignTest.kt b/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/test/kotlin/dev/sigstore/gradle/SigstoreSignTest.kt
index 77978f96..e7eb9299 100644
--- a/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/test/kotlin/dev/sigstore/gradle/SigstoreSignTest.kt
+++ b/sigstore-gradle/sigstore-gradle-sign-base-plugin/src/test/kotlin/dev/sigstore/gradle/SigstoreSignTest.kt
@@ -55,6 +55,7 @@ class SigstoreSignTest: BaseGradleTest() {
             """.trimIndent()
         )
         enableConfigurationCache(case.gradle)
+        enableProjectIsolation(case.gradle)
         prepare(case.gradle.version, "signFile", "-s")
             .build()
         assertThat(projectDir.resolve("build/helloProps.txt.sigstore.json"))
diff --git a/sigstore-gradle/sigstore-gradle-sign-plugin/src/test/kotlin/dev/sigstore/gradle/RemoveSigstoreAscTest.kt b/sigstore-gradle/sigstore-gradle-sign-plugin/src/test/kotlin/dev/sigstore/gradle/RemoveSigstoreAscTest.kt
index bb648c53..b63b51fd 100644
--- a/sigstore-gradle/sigstore-gradle-sign-plugin/src/test/kotlin/dev/sigstore/gradle/RemoveSigstoreAscTest.kt
+++ b/sigstore-gradle/sigstore-gradle-sign-plugin/src/test/kotlin/dev/sigstore/gradle/RemoveSigstoreAscTest.kt
@@ -41,7 +41,7 @@ class RemoveSigstoreAscTest : BaseGradleTest() {
                     // Gradle < 8.1 + configuration cache=on which is incompatible with signing plugin.
                     listOf(
                         TestedGradleAndSigstoreJava(
-                            TestedGradle(GradleVersion.version("8.1"), ConfigurationCache.OFF),
+                            TestedGradle(GradleVersion.version("8.1"), ConfigurationCache.OFF, ProjectIsolation.OFF),
                             SIGSTORE_JAVA_CURRENT_VERSION
                         )
                     )
@@ -147,6 +147,7 @@ class RemoveSigstoreAscTest : BaseGradleTest() {
             """.trimIndent()
         )
         enableConfigurationCache(case.gradle)
+        enableProjectIsolation(case.gradle)
     }
 
     private fun SoftAssertions.assertSignatures(name: String, expectSigstoreAsc: Boolean = false) {
diff --git a/sigstore-gradle/sigstore-gradle-sign-plugin/src/test/kotlin/dev/sigstore/gradle/SigstorePublishSignTest.kt b/sigstore-gradle/sigstore-gradle-sign-plugin/src/test/kotlin/dev/sigstore/gradle/SigstorePublishSignTest.kt
index d6552cb5..85597c69 100644
--- a/sigstore-gradle/sigstore-gradle-sign-plugin/src/test/kotlin/dev/sigstore/gradle/SigstorePublishSignTest.kt
+++ b/sigstore-gradle/sigstore-gradle-sign-plugin/src/test/kotlin/dev/sigstore/gradle/SigstorePublishSignTest.kt
@@ -65,6 +65,7 @@ class SigstorePublishSignTest : BaseGradleTest() {
             """.trimIndent()
         )
         enableConfigurationCache(case.gradle)
+        enableProjectIsolation(case.gradle)
         prepare(case.gradle.version, "publishAllPublicationsToTmpRepository", "-s")
             .build()
 
diff --git a/sigstore-testkit/src/main/kotlin/dev/sigstore/testkit/BaseGradleTest.kt b/sigstore-testkit/src/main/kotlin/dev/sigstore/testkit/BaseGradleTest.kt
index b761b1d2..06781f27 100644
--- a/sigstore-testkit/src/main/kotlin/dev/sigstore/testkit/BaseGradleTest.kt
+++ b/sigstore-testkit/src/main/kotlin/dev/sigstore/testkit/BaseGradleTest.kt
@@ -29,11 +29,15 @@ import org.junit.jupiter.params.provider.Arguments
 import org.junit.jupiter.params.provider.Arguments.arguments
 import java.io.File
 import java.nio.file.Path
+import kotlin.io.path.appendText
 
 open class BaseGradleTest {
     enum class ConfigurationCache {
         ON, OFF
     }
+    enum class ProjectIsolation {
+        ON, OFF
+    }
 
     // to debug these tests, add .withDebug(true) before running a test in debug mode
     protected val gradleRunner = GradleRunner.create().withPluginClasspath()
@@ -63,16 +67,16 @@ open class BaseGradleTest {
             if (!isCI) {
                 // Execute a single combination only when running locally
                 return listOf(
-                    TestedGradle(gradleVersions().first(), ConfigurationCache.ON)
+                    TestedGradle(gradleVersions().first(), ConfigurationCache.ON, ProjectIsolation.ON)
                 )
             }
             return buildList {
                 addAll(
-                    gradleVersions().map { TestedGradle(it, ConfigurationCache.ON) }
+                    gradleVersions().map { TestedGradle(it, ConfigurationCache.ON, ProjectIsolation.ON) }
                 )
                 // Test the first and the last version without configuration cache
-                add(TestedGradle(gradleVersions().first(), ConfigurationCache.OFF))
-                add(TestedGradle(gradleVersions().last(), ConfigurationCache.OFF))
+                add(TestedGradle(gradleVersions().first(), ConfigurationCache.OFF, ProjectIsolation.OFF))
+                add(TestedGradle(gradleVersions().last(), ConfigurationCache.OFF, ProjectIsolation.OFF))
             }
         }
 
@@ -202,6 +206,23 @@ open class BaseGradleTest {
         )
     }
 
+    protected fun enableProjectIsolation(
+        gradle: TestedGradle,
+    ) {
+        if (gradle.projectIsolation != ProjectIsolation.ON) {
+            return
+        }
+        require(gradle.configurationCache == ConfigurationCache.ON) {
+            "Project isolation requires Configuration Cache."
+        }
+        projectDir.resolve("gradle.properties").appendText(
+            """
+
+            org.gradle.unsafe.isolated-projects=true
+            """.trimIndent()
+        )
+    }
+
     protected fun assertSoftly(body: SoftAssertions.() -> Unit) =
         SoftAssertions.assertSoftly(body)
 
diff --git a/sigstore-testkit/src/main/kotlin/dev/sigstore/testkit/TestedGradle.kt b/sigstore-testkit/src/main/kotlin/dev/sigstore/testkit/TestedGradle.kt
index b6ee684b..8990fae7 100644
--- a/sigstore-testkit/src/main/kotlin/dev/sigstore/testkit/TestedGradle.kt
+++ b/sigstore-testkit/src/main/kotlin/dev/sigstore/testkit/TestedGradle.kt
@@ -23,5 +23,6 @@ import org.gradle.util.GradleVersion
  */
 data class TestedGradle(
     val version: GradleVersion,
-    val configurationCache: BaseGradleTest.ConfigurationCache
+    val configurationCache: BaseGradleTest.ConfigurationCache,
+    val projectIsolation: BaseGradleTest.ProjectIsolation,
 )