diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/FileTransferHandler.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/FileTransferHandler.java
index 849988a6c3..adfcab6196 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/FileTransferHandler.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/FileTransferHandler.java
@@ -433,13 +433,13 @@ public CreateFileMessage initiateUpload(byte[] fileAsByteArray, FileType.FILETYP
         public String getOutputPath() {
             // [FILE_TYPE]/
             final StringBuilder sb = new StringBuilder(getFiletype().name());
-            sb.append("/");
+            sb.append(File.separator);
 
             // If we have a valid date, place the file inside a folder for each year
             // [YEAR]/
             if (fileDate.getTime() != GarminTimeUtils.GARMIN_TIME_EPOCH * 1000L) {
                 sb.append(SDF_YEAR.format(fileDate));
-                sb.append("/");
+                sb.append(File.separator);
             }
 
             // Finally, the filename
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/fit/FitImporter.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/fit/FitImporter.java
index 5d827d505e..44167e100b 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/fit/FitImporter.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/fit/FitImporter.java
@@ -733,13 +733,13 @@ public class FitImporter {
         } else {
             sb.append("NULL");
         }
-        sb.append("/");
+        sb.append(File.separator);
 
         // If we have a valid date, place the file inside a folder for each year
         // [YEAR]/
         if (fileId.getTimeCreated() != null && fileId.getTimeCreated() != 0) {
             sb.append(SDF_YEAR.format(new Date(fileId.getTimeCreated() * 1000L)));
-            sb.append("/");
+            sb.append(File.separator);
         }
 
         // [FILE_TYPE]_[yyyy-MM-dd_HH-mm-ss]_[INDEX].[fit/bin]
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/xiaomi/activity/XiaomiActivityFileId.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/xiaomi/activity/XiaomiActivityFileId.java
index 90c53de7c4..dd43edee0e 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/xiaomi/activity/XiaomiActivityFileId.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/xiaomi/activity/XiaomiActivityFileId.java
@@ -158,7 +158,7 @@ public class XiaomiActivityFileId implements Comparable<XiaomiActivityFileId> {
 
         // Year
         sb.append(SDF_YEAR.format(getTimestamp()));
-        sb.append("/");
+        sb.append(File.separator);
 
         // Type
         final Type typeName = Type.fromCode(type);
@@ -166,7 +166,7 @@ public class XiaomiActivityFileId implements Comparable<XiaomiActivityFileId> {
         if (typeName == Type.UNKNOWN) {
             sb.append("_").append(String.format("%02X", type));
         }
-        sb.append("/");
+        sb.append(File.separator);
 
         // Subtype
         final Subtype subtypeName = Subtype.fromCode(typeName, subtype);
@@ -174,7 +174,7 @@ public class XiaomiActivityFileId implements Comparable<XiaomiActivityFileId> {
         if (subtypeName == Subtype.UNKNOWN) {
             sb.append("_").append(String.format("%02X", subtype));
         }
-        sb.append("/");
+        sb.append(File.separator);
 
         // DetailType
         final DetailType detailTypeName = DetailType.fromCode(detailType);
@@ -182,7 +182,7 @@ public class XiaomiActivityFileId implements Comparable<XiaomiActivityFileId> {
         if (detailTypeName == DetailType.UNKNOWN) {
             sb.append("_").append(String.format("%02X", subtype));
         }
-        sb.append("/");
+        sb.append(File.separator);
 
         // Filename
         sb.append(String.format(