diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainIntentService.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainIntentService.java
index 9f769759e..bf6a62782 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainIntentService.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainIntentService.java
@@ -135,7 +135,7 @@ public class KeychainIntentService extends IntentService implements Progressable
         private static final IOType[] values = values();
 
         public static IOType fromInt(int n) {
-            if(n >= values.length) {
+            if(n < 0 || n >= values.length) {
                 return UNKNOWN;
             } else {
                 return values[n];
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainIntentServiceHandler.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainIntentServiceHandler.java
index c102acc32..bd047518d 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainIntentServiceHandler.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainIntentServiceHandler.java
@@ -44,7 +44,7 @@ public class KeychainIntentServiceHandler extends Handler {
 
         public static MessageStatus fromInt(int n)
         {
-            if(n >= values.length) {
+            if(n < 0 || n >= values.length) {
                 return UNKNOWN;
             } else {
                 return values[n];