diff --git a/app/autodiscovery/build.gradle b/app/autodiscovery/build.gradle
index 7ad0357180..06632c0880 100644
--- a/app/autodiscovery/build.gradle
+++ b/app/autodiscovery/build.gradle
@@ -39,6 +39,10 @@ android {
         targetCompatibility javaVersion
     }
 
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
+
     testOptions {
         unitTests {
             includeAndroidResources = true
diff --git a/app/core/build.gradle b/app/core/build.gradle
index 50961c8844..c704a38067 100644
--- a/app/core/build.gradle
+++ b/app/core/build.gradle
@@ -55,6 +55,10 @@ android {
         targetCompatibility javaVersion
     }
 
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
+
     testOptions {
         unitTests {
             includeAndroidResources = true
diff --git a/app/crypto-openpgp/build.gradle b/app/crypto-openpgp/build.gradle
index 97fbee5bd2..fc24fcfd7b 100644
--- a/app/crypto-openpgp/build.gradle
+++ b/app/crypto-openpgp/build.gradle
@@ -27,4 +27,8 @@ android {
         sourceCompatibility javaVersion
         targetCompatibility javaVersion
     }
+
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
 }
diff --git a/app/k9mail/build.gradle b/app/k9mail/build.gradle
index 0b62efed4d..c05e047808 100644
--- a/app/k9mail/build.gradle
+++ b/app/k9mail/build.gradle
@@ -99,6 +99,10 @@ android {
         targetCompatibility javaVersion
     }
 
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
+
     testOptions {
         unitTests {
             includeAndroidResources = true
diff --git a/app/storage/build.gradle b/app/storage/build.gradle
index 2b17b69a99..0183005690 100644
--- a/app/storage/build.gradle
+++ b/app/storage/build.gradle
@@ -39,6 +39,10 @@ android {
         targetCompatibility javaVersion
     }
 
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
+
     testOptions {
         unitTests {
             includeAndroidResources = true
diff --git a/app/testing/build.gradle b/app/testing/build.gradle
index 61fc019c17..d2d5016bfc 100644
--- a/app/testing/build.gradle
+++ b/app/testing/build.gradle
@@ -31,4 +31,8 @@ android {
         sourceCompatibility javaVersion
         targetCompatibility javaVersion
     }
+
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
 }
diff --git a/app/ui/build.gradle b/app/ui/build.gradle
index ee4f482e4c..eebba79594 100644
--- a/app/ui/build.gradle
+++ b/app/ui/build.gradle
@@ -79,6 +79,10 @@ android {
         targetCompatibility javaVersion
     }
 
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
+
     testOptions {
         unitTests {
             includeAndroidResources = true
diff --git a/backend/api/build.gradle b/backend/api/build.gradle
index fa7fcda330..463cb2b5dd 100644
--- a/backend/api/build.gradle
+++ b/backend/api/build.gradle
@@ -24,4 +24,8 @@ android {
         sourceCompatibility javaVersion
         targetCompatibility javaVersion
     }
+
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
 }
diff --git a/backend/imap/build.gradle b/backend/imap/build.gradle
index 0dbc00971c..c860ca69c8 100644
--- a/backend/imap/build.gradle
+++ b/backend/imap/build.gradle
@@ -42,4 +42,8 @@ android {
         sourceCompatibility javaVersion
         targetCompatibility javaVersion
     }
+
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
 }
diff --git a/backend/pop3/build.gradle b/backend/pop3/build.gradle
index 3097483e81..a26b29c9cd 100644
--- a/backend/pop3/build.gradle
+++ b/backend/pop3/build.gradle
@@ -42,4 +42,8 @@ android {
         sourceCompatibility javaVersion
         targetCompatibility javaVersion
     }
+
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
 }
diff --git a/backend/webdav/build.gradle b/backend/webdav/build.gradle
index 14fb138b30..6359676cb9 100644
--- a/backend/webdav/build.gradle
+++ b/backend/webdav/build.gradle
@@ -41,4 +41,8 @@ android {
         sourceCompatibility javaVersion
         targetCompatibility javaVersion
     }
+
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
 }
diff --git a/build.gradle b/build.gradle
index 41f62aad18..c53aeb6bb8 100644
--- a/build.gradle
+++ b/build.gradle
@@ -37,6 +37,7 @@ buildscript {
         ]
 
         javaVersion = JavaVersion.VERSION_1_8
+        kotlinJvmVersion = "1.8"
     }
 
     repositories {
diff --git a/mail/common/build.gradle b/mail/common/build.gradle
index 56a3cae769..48f31e00fe 100644
--- a/mail/common/build.gradle
+++ b/mail/common/build.gradle
@@ -50,4 +50,8 @@ android {
         sourceCompatibility javaVersion
         targetCompatibility javaVersion
     }
+
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
 }
diff --git a/mail/protocols/imap/build.gradle b/mail/protocols/imap/build.gradle
index d2a549a072..f24eaeb687 100644
--- a/mail/protocols/imap/build.gradle
+++ b/mail/protocols/imap/build.gradle
@@ -48,4 +48,8 @@ android {
         sourceCompatibility javaVersion
         targetCompatibility javaVersion
     }
+
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
 }
diff --git a/mail/testing/build.gradle b/mail/testing/build.gradle
index 16f0249647..5e80d796f4 100644
--- a/mail/testing/build.gradle
+++ b/mail/testing/build.gradle
@@ -27,4 +27,8 @@ android {
         sourceCompatibility javaVersion
         targetCompatibility javaVersion
     }
+
+    kotlinOptions {
+        jvmTarget = kotlinJvmVersion
+    }
 }