diff --git a/src/script/sign.cpp b/src/script/sign.cpp
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -455,6 +455,7 @@
     for (size_t i = 0; i < outputs.size(); ++i) {
         outputs[i].Merge(psbt.outputs[i]);
     }
+    unknown.insert(psbt.unknown.begin(), psbt.unknown.end());
 }
 
 bool PartiallySignedTransaction::IsSane() const {
diff --git a/test/functional/data/rpc_psbt.json b/test/functional/data/rpc_psbt.json
--- a/test/functional/data/rpc_psbt.json
+++ b/test/functional/data/rpc_psbt.json
@@ -70,6 +70,13 @@
                 "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"
             ],
             "result" : "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"
+        },
+        {
+            "combine" : [
+                "cHNidP8BAD8CAAAAAf//////////////////////////////////////////AAAAAAD/////AQAAAAAAAAAAA2oBAAAAAAAKDwECAwQFBgcICQ8BAgMEBQYHCAkKCwwNDg8ACg8BAgMEBQYHCAkPAQIDBAUGBwgJCgsMDQ4PAAoPAQIDBAUGBwgJDwECAwQFBgcICQoLDA0ODwA=",
+                "cHNidP8BAD8CAAAAAf//////////////////////////////////////////AAAAAAD/////AQAAAAAAAAAAA2oBAAAAAAAKDwECAwQFBgcIEA8BAgMEBQYHCAkKCwwNDg8ACg8BAgMEBQYHCBAPAQIDBAUGBwgJCgsMDQ4PAAoPAQIDBAUGBwgQDwECAwQFBgcICQoLDA0ODwA="
+            ],
+            "result" : "cHNidP8BAD8CAAAAAf//////////////////////////////////////////AAAAAAD/////AQAAAAAAAAAAA2oBAAAAAAAKDwECAwQFBgcICQ8BAgMEBQYHCAkKCwwNDg8KDwECAwQFBgcIEA8BAgMEBQYHCAkKCwwNDg8ACg8BAgMEBQYHCAkPAQIDBAUGBwgJCgsMDQ4PCg8BAgMEBQYHCBAPAQIDBAUGBwgJCgsMDQ4PAAoPAQIDBAUGBwgJDwECAwQFBgcICQoLDA0ODwoPAQIDBAUGBwgQDwECAwQFBgcICQoLDA0ODwA="
         }
     ],
     "finalizer" : [