diff --git a/libcanard/canard.c b/libcanard/canard.c
index 863de50..eadf27c 100644
--- a/libcanard/canard.c
+++ b/libcanard/canard.c
@@ -1238,6 +1238,30 @@ int8_t canardRxUnsubscribe(CanardInstance* const    ins,
     return out;
 }
 
+int8_t canardRxHasSubscription(CanardInstance* const    ins,
+                               const CanardTransferKind transfer_kind,
+                               const CanardPortID       port_id)
+{
+    int8_t       out = -CANARD_ERROR_INVALID_ARGUMENT;
+    const size_t tk  = (size_t) transfer_kind;
+    if ((ins != NULL) && (tk < CANARD_NUM_TRANSFER_KINDS))
+    {
+        CanardPortID                      port_id_mutable = port_id;
+        const CanardRxSubscription* const sub             = (const CanardRxSubscription*) (void*)
+            cavlSearch(&ins->rx_subscriptions[tk], &port_id_mutable, &rxSubscriptionPredicateOnPortID, NULL);
+        if (sub != NULL)
+        {
+            CANARD_ASSERT(sub->port_id == port_id);
+            out = 1;
+        }
+        else
+        {
+            out = 0;
+        }
+    }
+    return out;
+}
+
 CanardFilter canardMakeFilterForSubject(const CanardPortID subject_id)
 {
     CanardFilter out = {0};
diff --git a/libcanard/canard.h b/libcanard/canard.h
index 0f1b5a7..9cdcfce 100644
--- a/libcanard/canard.h
+++ b/libcanard/canard.h
@@ -649,6 +649,10 @@ int8_t canardRxUnsubscribe(CanardInstance* const    ins,
                            const CanardTransferKind transfer_kind,
                            const CanardPortID       port_id);
 
+int8_t canardRxHasSubscription(CanardInstance* const    ins,
+                               const CanardTransferKind transfer_kind,
+                               const CanardPortID       port_id);
+
 /// Utilities for generating CAN controller hardware acceptance filter configurations
 /// to accept specific subjects, services, or nodes.
 ///
diff --git a/tests/helpers.hpp b/tests/helpers.hpp
index 618f3c8..7e4ba20 100644
--- a/tests/helpers.hpp
+++ b/tests/helpers.hpp
@@ -200,6 +200,11 @@ class Instance
         return canardRxUnsubscribe(&canard_, transfer_kind, port_id);
     }
 
+    [[nodiscard]] auto rxHasSubscription(const CanardTransferKind transfer_kind, const CanardPortID port_id)
+    {
+        return canardRxHasSubscription(&canard_, transfer_kind, port_id);
+    }
+
     /// The items are sorted by port-ID.
     [[nodiscard]] auto getSubs(const CanardTransferKind tk) const -> std::vector<const CanardRxSubscription*>
     {
diff --git a/tests/test_public_rx.cpp b/tests/test_public_rx.cpp
index 932d654..4f45c3a 100644
--- a/tests/test_public_rx.cpp
+++ b/tests/test_public_rx.cpp
@@ -49,8 +49,11 @@ TEST_CASE("RxBasic0")
 
     // Create a message subscription.
     CanardRxSubscription sub_msg{};
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(1 == ins.rxSubscribe(CanardTransferKindMessage, 0b0110011001100, 32, 2'000'000, sub_msg));  // New.
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(0 == ins.rxSubscribe(CanardTransferKindMessage, 0b0110011001100, 16, 1'000'000, sub_msg));  // Replaced.
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(ins.getMessageSubs().at(0) == &sub_msg);
     REQUIRE(ins.getMessageSubs().at(0)->port_id == 0b0110011001100);
     REQUIRE(ins.getMessageSubs().at(0)->extent == 16);
@@ -61,7 +64,9 @@ TEST_CASE("RxBasic0")
 
     // Create a request subscription.
     CanardRxSubscription sub_req{};
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindRequest, 0b0000110011));
     REQUIRE(1 == ins.rxSubscribe(CanardTransferKindRequest, 0b0000110011, 20, 3'000'000, sub_req));
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindRequest, 0b0000110011));
     REQUIRE(ins.getMessageSubs().at(0) == &sub_msg);
     REQUIRE(ins.getResponseSubs().empty());
     REQUIRE(ins.getRequestSubs().at(0) == &sub_req);
@@ -72,7 +77,9 @@ TEST_CASE("RxBasic0")
 
     // Create a response subscription.
     CanardRxSubscription sub_res{};
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindResponse, 0b0000111100));
     REQUIRE(1 == ins.rxSubscribe(CanardTransferKindResponse, 0b0000111100, 10, 100'000, sub_res));
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindResponse, 0b0000111100));
     REQUIRE(ins.getMessageSubs().at(0) == &sub_msg);
     REQUIRE(ins.getResponseSubs().at(0) == &sub_res);
     REQUIRE(ins.getResponseSubs().at(0)->port_id == 0b0000111100);
@@ -83,7 +90,9 @@ TEST_CASE("RxBasic0")
 
     // Create a second response subscription. It will come before the one we added above due to lower port-ID.
     CanardRxSubscription sub_res2{};
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindResponse, 0b0000000000));
     REQUIRE(1 == ins.rxSubscribe(CanardTransferKindResponse, 0b0000000000, 10, 1'000, sub_res2));
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindResponse, 0b0000000000));
     REQUIRE(ins.getMessageSubs().at(0) == &sub_msg);
     REQUIRE(ins.getResponseSubs().at(0) == &sub_res2);
     REQUIRE(ins.getResponseSubs().at(0)->port_id == 0b0000000000);
@@ -165,8 +174,11 @@ TEST_CASE("RxBasic0")
     REQUIRE(ins.getAllocator().getTotalAllocatedAmount() == (3 * sizeof(RxSession) + 16 + 20));
 
     // Destroy the message subscription and the buffer to free up memory.
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(1 == ins.rxUnsubscribe(CanardTransferKindMessage, 0b0110011001100));
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(0 == ins.rxUnsubscribe(CanardTransferKindMessage, 0b0110011001100));  // Repeat, nothing to do.
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(ins.getAllocator().getNumAllocatedFragments() == 4);
     REQUIRE(ins.getAllocator().getTotalAllocatedAmount() == (2 * sizeof(RxSession) + 16 + 20));
     ins.getAllocator().deallocate(msg_payload);
@@ -198,12 +210,21 @@ TEST_CASE("RxBasic0")
     REQUIRE(subscription == nullptr);
 
     // Unsubscribe.
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindRequest, 0b0000110011));
     REQUIRE(1 == ins.rxUnsubscribe(CanardTransferKindRequest, 0b0000110011));
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindRequest, 0b0000110011));
     REQUIRE(0 == ins.rxUnsubscribe(CanardTransferKindRequest, 0b0000110011));
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindRequest, 0b0000110011));
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindResponse, 0b0000111100));
     REQUIRE(1 == ins.rxUnsubscribe(CanardTransferKindResponse, 0b0000111100));
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindResponse, 0b0000111100));
     REQUIRE(0 == ins.rxUnsubscribe(CanardTransferKindResponse, 0b0000111100));
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindResponse, 0b0000111100));
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindResponse, 0b0000000000));
     REQUIRE(1 == ins.rxUnsubscribe(CanardTransferKindResponse, 0b0000000000));
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindResponse, 0b0000000000));
     REQUIRE(0 == ins.rxUnsubscribe(CanardTransferKindResponse, 0b0000000000));
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindResponse, 0b0000000000));
 }
 
 TEST_CASE("RxAnonymous")
@@ -239,7 +260,9 @@ TEST_CASE("RxAnonymous")
     void* const          my_user_reference = &ins;
     CanardRxSubscription sub_msg{};
     sub_msg.user_reference = my_user_reference;
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(1 == ins.rxSubscribe(CanardTransferKindMessage, 0b0110011001100, 16, 2'000'000, sub_msg));  // New.
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
 
     // Accepted anonymous message.
     subscription = nullptr;
@@ -358,7 +381,9 @@ TEST_CASE("Issue189")  // https://github.com/OpenCyphal/libcanard/issues/189
 
     // Create a message subscription.
     CanardRxSubscription sub_msg{};
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(1 == ins.rxSubscribe(CanardTransferKindMessage, 0b0110011001100, 50, 1'000'000, sub_msg));
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(ins.getMessageSubs().at(0) == &sub_msg);
     REQUIRE(ins.getMessageSubs().at(0)->port_id == 0b0110011001100);
     REQUIRE(ins.getMessageSubs().at(0)->extent == 50);
@@ -465,7 +490,9 @@ TEST_CASE("Issue212")
 
     // Create a message subscription with the transfer-ID timeout of just one microsecond.
     CanardRxSubscription sub_msg{};
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(1 == ins.rxSubscribe(CanardTransferKindMessage, 0b0110011001100, 50, 1, sub_msg));
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(ins.getMessageSubs().at(0) == &sub_msg);
     REQUIRE(ins.getMessageSubs().at(0)->port_id == 0b0110011001100);
     REQUIRE(ins.getMessageSubs().at(0)->extent == 50);
@@ -569,7 +596,9 @@ TEST_CASE("RxFixedTIDWithSmallTimeout")
 
     // Create a message subscription with the transfer-ID timeout of just five microseconds.
     CanardRxSubscription sub_msg{};
+    REQUIRE(0 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(1 == ins.rxSubscribe(CanardTransferKindMessage, 0b0110011001100, 50, 5, sub_msg));
+    REQUIRE(1 == ins.rxHasSubscription(CanardTransferKindMessage, 0b0110011001100));
     REQUIRE(ins.getMessageSubs().at(0) == &sub_msg);
     REQUIRE(ins.getMessageSubs().at(0)->port_id == 0b0110011001100);
     REQUIRE(ins.getMessageSubs().at(0)->extent == 50);