diff --git a/app/src/main/java/eu/faircode/email/ActivityDmarc.java b/app/src/main/java/eu/faircode/email/ActivityDmarc.java
index e84b9c1c91..9d2ecd14ac 100644
--- a/app/src/main/java/eu/faircode/email/ActivityDmarc.java
+++ b/app/src/main/java/eu/faircode/email/ActivityDmarc.java
@@ -272,9 +272,11 @@ public class ActivityDmarc extends ActivityBase {
                                                             ip = ip.toLowerCase(Locale.ROOT);
                                                             if (ip.startsWith("ip4:") || ip.startsWith("ip6:")) {
                                                                 String[] net = ip.substring(4).split("/");
-                                                                if (net.length != 2)
+                                                                if (net.length > 2)
                                                                     continue;
-                                                                Integer prefix = Helper.parseInt(net[1]);
+                                                                Integer prefix = ip.startsWith("ip4:") ? 32 : 64;
+                                                                if (net.length == 2)
+                                                                    prefix = Helper.parseInt(net[1]);
                                                                 if (prefix == null)
                                                                     continue;
                                                                 if (ConnectionHelper.inSubnet(text, net[0], prefix)) {