diff --git a/src/org/fdroid/fdroid/DB.java b/src/org/fdroid/fdroid/DB.java
index 076841ba5..c2545cc66 100644
--- a/src/org/fdroid/fdroid/DB.java
+++ b/src/org/fdroid/fdroid/DB.java
@@ -33,6 +33,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.concurrent.Semaphore;
 
@@ -1378,7 +1379,7 @@ public class DB {
         if (fingerprint == null) {
             fingerprint = calcedFingerprint;
         } else if (calcedFingerprint != null) {
-            fingerprint = fingerprint.toUpperCase();
+            fingerprint = fingerprint.toUpperCase(Locale.ENGLISH);
             if (!fingerprint.equals(calcedFingerprint)) {
                 throw new SecurityException("Given fingerprint does not match calculated one! ("
                         + fingerprint + " != " + calcedFingerprint);
diff --git a/src/org/fdroid/fdroid/Hasher.java b/src/org/fdroid/fdroid/Hasher.java
index 16ec1d024..fe874249c 100644
--- a/src/org/fdroid/fdroid/Hasher.java
+++ b/src/org/fdroid/fdroid/Hasher.java
@@ -28,6 +28,7 @@ import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.security.cert.Certificate;
 import java.security.cert.CertificateEncodingException;
+import java.util.Locale;
 
 public class Hasher {
 
@@ -88,7 +89,7 @@ public class Hasher {
         if (hashCache == null) getHash();
         if (otherHash == null || hashCache.equals(""))
             return false;
-        return hashCache.equals(otherHash.toLowerCase());
+        return hashCache.equals(otherHash.toLowerCase(Locale.ENGLISH));
     }
 
     public void reset() {