diff --git a/proguard-rules-consumer-jna.pro b/proguard-rules-consumer-jna.pro
index 444bdc2749..2a3934c837 100644
--- a/proguard-rules-consumer-jna.pro
+++ b/proguard-rules-consumer-jna.pro
@@ -4,4 +4,12 @@
 # See https://github.com/java-native-access/jna/blob/master/www/FrequentlyAskedQuestions.md#jna-on-android
 -dontwarn java.awt.*
 -keep class com.sun.jna.* { *; }
--keepclassmembers class * extends com.sun.jna.* { public *; }
\ No newline at end of file
+-keep class * extends com.sun.jna.* { *; }
+-keepclassmembers class * extends com.sun.jna.* { public *; }
+
+####################################################################################################
+# Add explicit keep rules for Nimbus RustBuffer and related structs to avoid
+# overly-aggressive optimization when R8 fullMode is enabled, leading to crashes.
+####################################################################################################
+-keepattributes RuntimeVisibleAnnotations,RuntimeInvisibleAnnotations,RuntimeVisibleTypeAnnotations,RuntimeInvisibleTypeAnnotations,AnnotationDefault,InnerClasses,EnclosingMethod,Signature
+-keep class org.mozilla.experiments.nimbus.internal.** { *; }