diff --git a/lightningd/peer_htlcs.c b/lightningd/peer_htlcs.c
index da4c69b4d..2185046e3 100644
--- a/lightningd/peer_htlcs.c
+++ b/lightningd/peer_htlcs.c
@@ -826,6 +826,33 @@ static u8 *convert_failcode(const tal_t *ctx,
 	}
 }
 
+static void
+htlc_accepted_hook_try_resolve(struct htlc_accepted_hook_payload *request,
+			       struct preimage *payment_preimage)
+{
+	struct sha256 payment_hash;
+	struct htlc_in *hin = request->hin;
+	u8 *unknown_details;
+	/* Verify that the provided secret hashes to what we need. */
+	sha256(&payment_hash, payment_preimage, sizeof(struct preimage));
+
+	if (!sha256_eq(&payment_hash, &hin->payment_hash)) {
+		log_broken(
+		    request->channel->log,
+		    "Plugin returned a preimage (sha256(%s) = %s) that doesn't "
+		    "match the HTLC hash (%s) it tries to resolve.",
+		    type_to_string(tmpctx, struct preimage, payment_preimage),
+		    type_to_string(tmpctx, struct sha256, &payment_hash),
+		    type_to_string(tmpctx, struct sha256, &hin->payment_hash));
+
+		unknown_details = tal_arr(NULL, u8, 0);
+		towire_u16(&unknown_details, 0x400f);
+		local_fail_in_htlc(hin, take(unknown_details));
+	} else {
+		fulfill_htlc(hin, payment_preimage);
+	}
+}
+
 /**
  * Callback when a plugin answers to the htlc_accepted hook
  */
@@ -893,7 +920,7 @@ static bool htlc_accepted_hook_deserialize(struct htlc_accepted_hook_payload *re
 		if (!json_to_preimage(buffer, paykeytok, &payment_preimage))
 			fatal("Plugin specified an invalid 'payment_key': %s",
 			      json_tok_full(buffer, resulttok));
-		fulfill_htlc(hin, &payment_preimage);
+		htlc_accepted_hook_try_resolve(request, &payment_preimage);
 		return false;
 	} else {
 		fatal("Plugin responded with an unknown result to the "