diff --git a/api/system-current.txt b/api/system-current.txt
index b2030ec8a9114..aec8cc1d68ed7 100644
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -5214,7 +5214,7 @@ package android.os {
   }
 
   public static class Build.VERSION {
-    field public static final String PREVIEW_SDK_FINGERPRINT;
+    field @NonNull public static final String PREVIEW_SDK_FINGERPRINT;
   }
 
   public final class ConfigUpdate {
diff --git a/core/java/android/os/Build.java b/core/java/android/os/Build.java
index 0425c6234a049..0de4ddca04944 100755
--- a/core/java/android/os/Build.java
+++ b/core/java/android/os/Build.java
@@ -306,7 +306,7 @@ public class Build {
          * @hide
          */
         @SystemApi
-        public static final String PREVIEW_SDK_FINGERPRINT = SystemProperties.get(
+        @NonNull public static final String PREVIEW_SDK_FINGERPRINT = SystemProperties.get(
                 "ro.build.version.preview_sdk_fingerprint", "REL");
 
         /**