diff --git a/src/main/java/com/android/tools/r8/utils/InternalOptions.java b/src/main/java/com/android/tools/r8/utils/InternalOptions.java
index c5aa86e..289ccdb 100644
--- a/src/main/java/com/android/tools/r8/utils/InternalOptions.java
+++ b/src/main/java/com/android/tools/r8/utils/InternalOptions.java
@@ -338,7 +338,8 @@
   // Optimization-related flags. These should conform to -dontoptimize and disableAllOptimizations.
   public boolean enableFieldBitAccessAnalysis =
       System.getProperty("com.android.tools.r8.fieldBitAccessAnalysis") != null;
-  public boolean enableVerticalClassMerging = true;
+  public boolean enableVerticalClassMerging =
+      System.getProperty("com.android.tools.r8.noVerticalClassMerging") == null;
   public boolean enableUnusedInterfaceRemoval = true;
   public boolean enableDevirtualization = true;
   public boolean enableEnumUnboxing = true;