diff --git a/k9mail/build.gradle b/k9mail/build.gradle
index ac4fe6ddb..59d8577c8 100644
--- a/k9mail/build.gradle
+++ b/k9mail/build.gradle
@@ -52,6 +52,7 @@ android {
         }
 
         debug {
+            applicationIdSuffix ".debug"
             testCoverageEnabled rootProject.testCoverage
         }
     }