diff --git a/dx/etc/mainDexClasses.rules b/dx/etc/mainDexClasses.rules
index a1ca931..0cd3842 100644
--- a/dx/etc/mainDexClasses.rules
+++ b/dx/etc/mainDexClasses.rules
@@ -13,3 +13,8 @@
   -keep public class * extends java.lang.annotation.Annotation {
    *;
   }
+# Keep old fashion tests in the main dex or they'll be silently ignored by InstrumentationTestRunner
+  -keep public class * extends android.test.InstrumentationTestCase {
+   <init>();
+  }
+
diff --git a/dx/shrinkedAndroid.proguard.flags b/dx/shrinkedAndroid.proguard.flags
index d72bb18..c22ec92 100644
--- a/dx/shrinkedAndroid.proguard.flags
+++ b/dx/shrinkedAndroid.proguard.flags
@@ -19,4 +19,6 @@
 }
 -keep public class java.lang.annotation.Annotation {
 }
+-keep public class * extends android.test.InstrumentationTestCase {
+}