diff --git a/README.md b/README.md
index 7f9b59730..fd25099f9 100644
--- a/README.md
+++ b/README.md
@@ -991,10 +991,11 @@ After that, you can run the `recordRoborazziDebug` task to generate screenshots
 
 ### Customizing the Preview screenshot test
 
-You can customize the generated test by adding the following configuration to your `build.gradle` file:
+You can customize the generated test by adding the following configuration to your `build.gradle.kts` file:
 
 ```kotlin
 roborazzi {
+  @OptIn(ExperimentalRoborazziApi::class)
   generateComposePreviewRobolectricTests {
     enable = true
     // The package names to scan for Composable Previews.
@@ -1013,6 +1014,12 @@ roborazzi {
 }
 ```
 
+> **Note**  
+> If you are using build.gradle instead of build.gradle.kts, you need to use the set method for each assignment, like
+> ```kotlin
+> generateComposePreviewRobolectricTests.packages.set(["com.example"])
+> ```
+
 ## Manually adding Compose Preview screenshot tests
 
 Roborazzi provides a helper function for ComposablePreviewScanner.
diff --git a/docs/topics/preview_support.md b/docs/topics/preview_support.md
index 1cf33e8f1..42ec43c28 100644
--- a/docs/topics/preview_support.md
+++ b/docs/topics/preview_support.md
@@ -22,10 +22,11 @@ After that, you can run the `recordRoborazziDebug` task to generate screenshots
 
 ### Customizing the Preview screenshot test
 
-You can customize the generated test by adding the following configuration to your `build.gradle` file:
+You can customize the generated test by adding the following configuration to your `build.gradle.kts` file:
 
 ```kotlin
 roborazzi {
+  @OptIn(ExperimentalRoborazziApi::class)
   generateComposePreviewRobolectricTests {
     enable = true
     // The package names to scan for Composable Previews.
@@ -44,6 +45,12 @@ roborazzi {
 }
 ```
 
+> **Note**  
+> If you are using build.gradle instead of build.gradle.kts, you need to use the set method for each assignment, like
+> ```kotlin
+> generateComposePreviewRobolectricTests.packages.set(["com.example"])
+> ```
+
 ## Manually adding Compose Preview screenshot tests
 
 Roborazzi provides a helper function for ComposablePreviewScanner.