diff --git a/tshark.c b/tshark.c
index b19cbf8dca..ee2be90fd3 100644
--- a/tshark.c
+++ b/tshark.c
@@ -1162,9 +1162,15 @@ main(int argc, char *argv[])
       }
       break;
     case 'j':
+      if (protocolfilter) {
+        cmdarg_err("-j or -J was already specified! Overwriting previous protocol filter");
+      }
       protocolfilter = wmem_strsplit(wmem_epan_scope(), optarg, " ", -1);
       break;
     case 'J':
+      if (protocolfilter) {
+        cmdarg_err("-j or -J was already specified! Overwriting previous protocol filter");
+      }
       protocolfilter_flags = PF_INCLUDE_CHILDREN;
       protocolfilter = wmem_strsplit(wmem_epan_scope(), optarg, " ", -1);
       break;