diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/agps/GarminAgpsFile.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/agps/GarminAgpsFile.java
index 673060f18..a8a566b50 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/agps/GarminAgpsFile.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/garmin/agps/GarminAgpsFile.java
@@ -5,6 +5,8 @@ import org.slf4j.LoggerFactory;
 
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
 import java.util.Arrays;
 import java.util.zip.GZIPInputStream;
 
@@ -18,7 +20,7 @@ public class GarminAgpsFile {
     private final byte[] bytes;
 
     public static final byte[] GZ_HEADER = new byte[]{(byte) 0x1f, (byte) 0x8b};
-    public static final byte[] CPE_RXNETWORKS_HEADER = new byte[]{(byte) 0x01, (byte) 0x00, (byte) 0x66};
+    public static final byte[] CPE_RXNETWORKS_HEADER = new byte[]{(byte) 0x01, (byte) 0x00};
     public static final byte[] CPE_SONY_HEADER = new byte[]{(byte) 0x2a, (byte) 0x12, (byte) 0xa0, (byte) 0x02};
 
     public GarminAgpsFile(final byte[] bytes) {
@@ -59,6 +61,24 @@ public class GarminAgpsFile {
                 LOG.error("Header in gz file is not agps rxnetworks: {}", GB.hexdump(header));
                 return false;
             }
+            final byte[] timestampBytes = new byte[4];
+            read = gzis.read(timestampBytes);
+            if (read != timestampBytes.length) {
+                LOG.error("Failed to read rxnetworks timestamp");
+                return false;
+            }
+            final int agpsTimestamp = ByteBuffer.wrap(timestampBytes).order(ByteOrder.BIG_ENDIAN).getInt();
+            final int currentTimestamp = (int) (System.currentTimeMillis() / 1000L);
+            final int agpsAge = currentTimestamp - agpsTimestamp;
+            if (agpsAge < 0) {
+                LOG.error("rxnetworks AGPS timestamp {} is in the future", agpsTimestamp);
+                return false;
+            }
+            if (agpsAge > 604800) {
+                LOG.error("rxnetworks AGPS timestamp {} is older than 7 days", agpsTimestamp);
+                return false;
+            }
+            LOG.debug("rx networks AGPS age: {}", agpsAge);
             return true;
         } catch (final IOException e) {
             LOG.error("Failed to decompress file as gzip", e);