diff --git a/src/main/java/org/opendevstack/component_catalog/server/controllers/CatalogApiAdapter.java b/src/main/java/org/opendevstack/component_catalog/server/controllers/CatalogApiAdapter.java
index b4330ce..80625e8 100644
--- a/src/main/java/org/opendevstack/component_catalog/server/controllers/CatalogApiAdapter.java
+++ b/src/main/java/org/opendevstack/component_catalog/server/controllers/CatalogApiAdapter.java
@@ -326,8 +326,15 @@ private  List<CatalogItemUserActionParameter> finalizeUserActionParameters(List<
         var baseNonCustomizableParamsNames = baseNonCustomizableUserActionParams.stream()
                 .map(CatalogItemUserActionParameter::getName)
                 .collect(Collectors.toSet());
+
         var customizableParamsPairs = customizableParamsPairsJoinedWithUserParams.stream()
-                .filter(pair -> !baseNonCustomizableParamsNames.contains(pair.getLeft().getName()))
+                .filter(pair -> {
+                    var userDefinedParamName = Optional.ofNullable(pair.getLeft())
+                            .map(CatalogItemUserActionParameter::getName)
+                            .orElse(Strings.EMPTY);
+
+                    return !baseNonCustomizableParamsNames.contains(userDefinedParamName);
+                })
                 .toList();
 
 
diff --git a/src/test/java/org/opendevstack/component_catalog/server/controllers/CatalogApiAdapterTest.java b/src/test/java/org/opendevstack/component_catalog/server/controllers/CatalogApiAdapterTest.java
index 13e47c5..739b4ea 100644
--- a/src/test/java/org/opendevstack/component_catalog/server/controllers/CatalogApiAdapterTest.java
+++ b/src/test/java/org/opendevstack/component_catalog/server/controllers/CatalogApiAdapterTest.java
@@ -430,6 +430,54 @@ void givenACatalogItem_AndItemContainsParameters_AndOneParameterSharesNameWithAN
         assertThat(parameterNonCustomizable.get().getDefaultValue().get()).isEqualTo("123");
     }
 
+    @Test
+    void givenACatalogItem_AndItemContainsParameters_AndOneParameterIsCustomizable_andCustomUserActionDoesNotDefineIt_whenFinalizeUserActions_thenCustomParameterAppers() {
+        // given
+        var customUserActionProvision = generateCustomUserActions();
+        var defaultUserActionProvision = generateDefaultUserActionEntity();
+        var parametersWithExtraOneList = new ArrayList<>(Arrays.asList(defaultUserActionProvision.getParameters()));
+        var extraCustomizableParameterName = "extraCustomizableParameter";
+        var extraCustomizableParameterValue = "123999";
+        var extraCustomizableParameter = UserActionEntityParameterMother.of(extraCustomizableParameterName,
+                "string",
+                true,
+                extraCustomizableParameterValue,
+                Collections.emptyList(),
+                List.of(UserActionEntityParameterLocationMother.of()),
+                Collections.emptyList(),
+                "Workflow to execute.",
+                "workflow placeholder",
+                "workflow hint",
+                true,
+                false,
+                List.of(UserActionEntityParameterValidationMother.of()));
+        parametersWithExtraOneList.add(extraCustomizableParameter);
+
+        defaultUserActionProvision.setParameters(parametersWithExtraOneList.toArray(UserActionEntityParameter[]::new));
+
+        var clusters = Collections.<String>emptyList();
+        var userGroups = Collections.<String>emptyList();
+        var projectKey = Strings.EMPTY;
+        var catalogItemId = Strings.EMPTY;
+
+        List<CatalogItemUserAction> customUserActions = List.of(customUserActionProvision);
+        UserActionEntity[] defaultUserActions = {defaultUserActionProvision};
+
+        // when
+        var mergedUserActions = catalogApiAdapter.finalizeUserActions(
+                customUserActions, defaultUserActions, clusters, userGroups, projectKey, catalogItemId);
+
+        // then
+        assertThat(mergedUserActions).hasSize(1);
+
+        var parameters =  mergedUserActions.getFirst().getParameters();
+
+        assertThat(parameters).hasSize(4);
+        var generatedExtraCustomizableParameter = parameters.stream().filter(p -> p.getName().equals(extraCustomizableParameterName)).findFirst();
+        assertThat(generatedExtraCustomizableParameter).isPresent();
+        assertThat(generatedExtraCustomizableParameter.get().getDefaultValue().get()).isEqualTo(extraCustomizableParameterValue);
+    }
+
     private UserActionEntity generateDefaultUserActionEntity() {
         var defaultParameter = UserActionEntityParameterMother.of();
         var defaultParameterNonCustomizable =  UserActionEntityParameterMother.of(PARAMETER_NON_CUSTOMIZABLE_NAME);