diff --git a/booking/src/main/java/org/dcsa/conformance/standards/booking/action/UC12_Shipper_CancelEntireBookingAction.java b/booking/src/main/java/org/dcsa/conformance/standards/booking/action/UC12_Shipper_CancelEntireBookingAction.java
index 2fbb2bc0..148ae396 100644
--- a/booking/src/main/java/org/dcsa/conformance/standards/booking/action/UC12_Shipper_CancelEntireBookingAction.java
+++ b/booking/src/main/java/org/dcsa/conformance/standards/booking/action/UC12_Shipper_CancelEntireBookingAction.java
@@ -61,6 +61,12 @@ protected Stream<? extends ConformanceCheck> createSubChecks() {
               getMatchedExchangeUuid(),
               BookingState.CANCELLED
             ),
+            new QueryParamCheck(
+              BookingRole::isShipper,
+              getMatchedExchangeUuid(),
+              "operation",
+              "cancelBooking"
+            ),
             new ApiHeaderCheck(
                 BookingRole::isShipper,
                 getMatchedExchangeUuid(),
diff --git a/booking/src/main/java/org/dcsa/conformance/standards/booking/action/UC9_Shipper_CancelBookingAmendment.java b/booking/src/main/java/org/dcsa/conformance/standards/booking/action/UC9_Shipper_CancelBookingAmendment.java
index 49a80bac..f2bce1ab 100644
--- a/booking/src/main/java/org/dcsa/conformance/standards/booking/action/UC9_Shipper_CancelBookingAmendment.java
+++ b/booking/src/main/java/org/dcsa/conformance/standards/booking/action/UC9_Shipper_CancelBookingAmendment.java
@@ -52,6 +52,12 @@ protected Stream<? extends ConformanceCheck> createSubChecks() {
           new UrlPathCheck(BookingRole::isShipper, getMatchedExchangeUuid(), "/v2/bookings/%s".formatted(cbrr)),
           new ResponseStatusCheck(
             BookingRole::isCarrier, getMatchedExchangeUuid(), expectedStatus),
+          new QueryParamCheck(
+            BookingRole::isShipper,
+            getMatchedExchangeUuid(),
+            "operation",
+            "cancelAmendment"
+          ),
           new ApiHeaderCheck(
             BookingRole::isShipper,
             getMatchedExchangeUuid(),
diff --git a/booking/src/main/java/org/dcsa/conformance/standards/booking/party/Shipper.java b/booking/src/main/java/org/dcsa/conformance/standards/booking/party/Shipper.java
index 717c050b..e545e27b 100644
--- a/booking/src/main/java/org/dcsa/conformance/standards/booking/party/Shipper.java
+++ b/booking/src/main/java/org/dcsa/conformance/standards/booking/party/Shipper.java
@@ -117,27 +117,29 @@ private void sendBookingRequest(JsonNode actionPrompt) {
   private void sendCancelEntireBooking(JsonNode actionPrompt) {
     log.info("Shipper.sendCancelEntireBooking(%s)".formatted(actionPrompt.toPrettyString()));
     String cbrr = actionPrompt.get("cbrr").asText();
-
+    Map<String, List<String>> queryParams =  Map.of("operation", List.of("cancelBooking"));
     asyncCounterpartPatch(
-        "/v2/bookings/%s?operation=cancelBooking".formatted(cbrr),
+        "/v2/bookings/%s".formatted(cbrr),
+        queryParams,
         new ObjectMapper()
             .createObjectNode()
             .put("bookingStatus", BookingState.CANCELLED.wireName()));
 
-    addOperatorLogEntry("Sent a cancel booking request of '%s'".formatted(cbrr));
+    addOperatorLogEntry("Sent a cancel amendment request of '%s'".formatted(cbrr));
   }
 
   private void sendCancelBookingAmendment(JsonNode actionPrompt) {
-    log.info("Shipper.sendCancelEntireBooking(%s)".formatted(actionPrompt.toPrettyString()));
+    log.info("Shipper.sendCancelBookingAmendment(%s)".formatted(actionPrompt.toPrettyString()));
     String cbrr = actionPrompt.get("cbrr").asText();
-
+    Map<String, List<String>> queryParams =  Map.of("operation", List.of("cancelAmendment"));
     asyncCounterpartPatch(
-      "/v2/bookings/%s?operation=cancelAmendment".formatted(cbrr),
+      "/v2/bookings/%s".formatted(cbrr),
+      queryParams,
       new ObjectMapper()
         .createObjectNode()
         .put("bookingStatus", BookingState.CANCELLED.wireName()));
 
-    addOperatorLogEntry("Sent a cancel booking request of '%s'".formatted(cbrr));
+    addOperatorLogEntry("Sent a cancel amendment request of '%s'".formatted(cbrr));
   }
 
   private void sendUpdatedBooking(JsonNode actionPrompt) {
diff --git a/core/src/main/java/org/dcsa/conformance/core/party/ConformanceParty.java b/core/src/main/java/org/dcsa/conformance/core/party/ConformanceParty.java
index 9e09ee84..da12baf3 100644
--- a/core/src/main/java/org/dcsa/conformance/core/party/ConformanceParty.java
+++ b/core/src/main/java/org/dcsa/conformance/core/party/ConformanceParty.java
@@ -183,6 +183,10 @@ protected void asyncCounterpartPatch(String path, JsonNode jsonBody) {
     asyncCounterpartPatch(path, jsonBody, conformanceResponse -> {});
   }
 
+  protected void asyncCounterpartPatch(String path, Map<String, ? extends Collection<String>> queryParams, JsonNode jsonBody) {
+    asyncCounterpartPatch(path, queryParams, jsonBody, conformanceResponse -> {});
+  }
+
   protected void asyncCounterpartPost(String path, JsonNode jsonBody) {
     asyncCounterpartPost(path, jsonBody, conformanceResponse -> {});
   }
@@ -195,6 +199,11 @@ protected void asyncCounterpartPatch(String path, JsonNode jsonBody, Consumer<Co
     _asyncCounterpartPatchPostOrPut("PATCH", path, Collections.emptyMap(), jsonBody, responseCallback);
   }
 
+  protected void asyncCounterpartPatch(String path,Map<String, ? extends Collection<String>> queryParams,
+                                       JsonNode jsonBody, Consumer<ConformanceResponse> responseCallback) {
+    _asyncCounterpartPatchPostOrPut("PATCH", path, queryParams, jsonBody, responseCallback);
+  }
+
   protected void asyncCounterpartPost(String path, JsonNode jsonBody, Consumer<ConformanceResponse> responseCallback) {
     _asyncCounterpartPatchPostOrPut("POST", path, Collections.emptyMap(), jsonBody, responseCallback);
   }