diff --git a/app/src/main/java/org/fdroid/fdroid/CleanCacheService.java b/app/src/main/java/org/fdroid/fdroid/CleanCacheService.java
index b912992a9..a1f5d6c9b 100644
--- a/app/src/main/java/org/fdroid/fdroid/CleanCacheService.java
+++ b/app/src/main/java/org/fdroid/fdroid/CleanCacheService.java
@@ -17,6 +17,7 @@ import org.apache.commons.io.FileUtils;
 import org.fdroid.fdroid.installer.ApkCache;
 
 import java.io.File;
+import java.util.concurrent.TimeUnit;
 
 /**
  * Handles cleaning up caches files that are not going to be used, and do not
@@ -33,9 +34,9 @@ public class CleanCacheService extends IntentService {
      */
     public static void schedule(Context context) {
         long keepTime = Preferences.get().getKeepCacheTime();
-        long interval = 604800000; // 1 day
+        long interval = TimeUnit.DAYS.toMillis(1);
         if (keepTime < interval) {
-            interval = keepTime * 1000;
+            interval = keepTime;
         }
 
         Intent intent = new Intent(context, CleanCacheService.class);
@@ -119,15 +120,15 @@ public class CleanCacheService extends IntentService {
 
     /**
      * Recursively delete files in {@code dir} that were last used
-     * {@code secondsAgo} seconds ago.  On {@code android-21} and newer, this
+     * {@code millisAgo} milliseconds ago.  On {@code android-21} and newer, this
      * is based on the last access of the file, on older Android versions, it is
      * based on the last time the file was modified, e.g. downloaded.
      *
      * @param dir        The directory to recurse in
-     * @param secondsAgo The number of seconds old that marks a file for deletion.
+     * @param millisAgo The number of milliseconds old that marks a file for deletion.
      */
     @TargetApi(21)
-    public static void clearOldFiles(File dir, long secondsAgo) {
+    public static void clearOldFiles(File dir, long millisAgo) {
         if (dir == null) {
             return;
         }
@@ -135,7 +136,7 @@ public class CleanCacheService extends IntentService {
         if (files == null) {
             return;
         }
-        long olderThan = System.currentTimeMillis() - (secondsAgo * 1000L);
+        long olderThan = System.currentTimeMillis() - millisAgo;
         for (File f : files) {
             if (f.isDirectory()) {
                 clearOldFiles(f, olderThan);
@@ -148,7 +149,7 @@ public class CleanCacheService extends IntentService {
             } else {
                 try {
                     StructStat stat = Os.lstat(f.getAbsolutePath());
-                    if (stat.st_atime < olderThan) {
+                    if ((stat.st_atime * 1000L) < olderThan) {
                         f.delete();
                     }
                 } catch (ErrnoException e) {
diff --git a/app/src/main/java/org/fdroid/fdroid/Preferences.java b/app/src/main/java/org/fdroid/fdroid/Preferences.java
index 0a7a9faad..3216f4c87 100644
--- a/app/src/main/java/org/fdroid/fdroid/Preferences.java
+++ b/app/src/main/java/org/fdroid/fdroid/Preferences.java
@@ -16,6 +16,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Random;
+import java.util.concurrent.TimeUnit;
 
 import info.guardianproject.netcipher.NetCipher;
 
@@ -30,11 +31,9 @@ public final class Preferences implements SharedPreferences.OnSharedPreferenceCh
 
     private static final String TAG = "Preferences";
 
-    private final Context context;
     private final SharedPreferences preferences;
 
     private Preferences(Context context) {
-        this.context = context;
         preferences = PreferenceManager.getDefaultSharedPreferences(context);
         preferences.registerOnSharedPreferenceChangeListener(this);
         if (preferences.getString(PREF_LOCAL_REPO_NAME, null) == null) {
@@ -72,7 +71,7 @@ public final class Preferences implements SharedPreferences.OnSharedPreferenceCh
     private static final int DEFAULT_UPD_HISTORY = 14;
     private static final boolean DEFAULT_PRIVILEGED_INSTALLER = false;
     //private static final boolean DEFAULT_LOCAL_REPO_BONJOUR = true;
-    private static final long DEFAULT_KEEP_CACHE_SECONDS = 86400;  // one day
+    private static final long DEFAULT_KEEP_CACHE_TIME = TimeUnit.DAYS.toMillis(1);  // one day
     private static final boolean DEFAULT_UNSTABLE_UPDATES = false;
     //private static final boolean DEFAULT_LOCAL_REPO_HTTPS = false;
     private static final boolean DEFAULT_INCOMP_VER = false;
@@ -136,14 +135,29 @@ public final class Preferences implements SharedPreferences.OnSharedPreferenceCh
     private static final String PREF_CACHE_APK = "cacheDownloaded";
 
     /**
-     * Time in seconds to keep cached files.  Anything that has been around longer will be deleted
+     * Time in millis to keep cached files.  Anything that has been around longer will be deleted
      */
     public long getKeepCacheTime() {
-        String value = preferences.getString(PREF_KEEP_CACHE_TIME, String.valueOf(DEFAULT_KEEP_CACHE_SECONDS));
+        String value = preferences.getString(PREF_KEEP_CACHE_TIME,
+                String.valueOf(DEFAULT_KEEP_CACHE_TIME));
+
+        // the first time this was migrated, it was botched, so reset to default
+        switch (value) {
+            case "3600":
+            case "86400":
+            case "604800":
+            case "2592000":
+            case "31449600":
+            case "2147483647":
+                SharedPreferences.Editor editor = preferences.edit();
+                editor.remove(PREF_KEEP_CACHE_TIME);
+                editor.apply();
+                return Preferences.DEFAULT_KEEP_CACHE_TIME;
+        }
 
         if (preferences.contains(PREF_CACHE_APK)) {
             if (preferences.getBoolean(PREF_CACHE_APK, false)) {
-                value = context.getString(R.string.keep_forever);
+                value = String.valueOf(Long.MAX_VALUE);
             }
             SharedPreferences.Editor editor = preferences.edit();
             editor.remove(PREF_CACHE_APK);
@@ -154,7 +168,7 @@ public final class Preferences implements SharedPreferences.OnSharedPreferenceCh
         try {
             return Long.parseLong(value);
         } catch (NumberFormatException e) {
-            return DEFAULT_KEEP_CACHE_SECONDS;
+            return DEFAULT_KEEP_CACHE_TIME;
         }
     }
 
diff --git a/app/src/main/res/values/donottranslate.xml b/app/src/main/res/values/donottranslate.xml
index 148db8f22..ed9644aef 100644
--- a/app/src/main/res/values/donottranslate.xml
+++ b/app/src/main/res/values/donottranslate.xml
@@ -26,12 +26,12 @@
     </string-array>
 
     <string-array name="keepCacheValues">
-        <item>3600</item>
-        <item>86400</item>
-        <item>604800</item>
-        <item>2592000</item>
-        <item>31449600</item>
-        <item>2147483647</item>
+        <item>3600000</item>
+        <item>86400000</item>
+        <item>604800000</item>
+        <item>2592000000</item>
+        <item>31536000000</item>
+        <item>9223372036854775807</item>
     </string-array>
 
     <string-array name="themeValues">
diff --git a/app/src/main/res/xml/preferences.xml b/app/src/main/res/xml/preferences.xml
index 454472b61..6f5b404f3 100644
--- a/app/src/main/res/xml/preferences.xml
+++ b/app/src/main/res/xml/preferences.xml
@@ -75,7 +75,7 @@
     <PreferenceCategory android:title="@string/other">
         <ListPreference android:title="@string/cache_downloaded"
             android:key="keepCacheFor"
-            android:defaultValue="86400"
+            android:defaultValue="86400000"
             android:entries="@array/keepCacheNames"
             android:entryValues="@array/keepCacheValues" />
         <CheckBoxPreference android:title="@string/expert"
diff --git a/app/src/test/java/org/fdroid/fdroid/CleanCacheServiceTest.java b/app/src/test/java/org/fdroid/fdroid/CleanCacheServiceTest.java
index 8494e6891..0c32ef893 100644
--- a/app/src/test/java/org/fdroid/fdroid/CleanCacheServiceTest.java
+++ b/app/src/test/java/org/fdroid/fdroid/CleanCacheServiceTest.java
@@ -46,12 +46,12 @@ public class CleanCacheServiceTest {
         assertTrue(second.createNewFile());
         assertTrue(second.exists());
 
-        CleanCacheService.clearOldFiles(dir, 3);
+        CleanCacheService.clearOldFiles(dir, 3000);
         assertFalse(first.exists());
         assertTrue(second.exists());
 
         Thread.sleep(7000);
-        CleanCacheService.clearOldFiles(dir, 3);
+        CleanCacheService.clearOldFiles(dir, 3000);
         assertFalse(first.exists());
         assertFalse(second.exists());
     }