diff --git a/src/main/java/eu/europa/ec/dgc/gateway/connector/DgcGatewayConnectorUtils.java b/src/main/java/eu/europa/ec/dgc/gateway/connector/DgcGatewayConnectorUtils.java
index 8473c94..f72a93d 100644
--- a/src/main/java/eu/europa/ec/dgc/gateway/connector/DgcGatewayConnectorUtils.java
+++ b/src/main/java/eu/europa/ec/dgc/gateway/connector/DgcGatewayConnectorUtils.java
@@ -29,6 +29,7 @@
 import eu.europa.ec.dgc.gateway.connector.model.QueryParameter;
 import eu.europa.ec.dgc.gateway.connector.model.TrustedIssuer;
 import eu.europa.ec.dgc.signing.SignedCertificateMessageParser;
+import eu.europa.ec.dgc.signing.SignedMessageParser;
 import eu.europa.ec.dgc.signing.SignedStringMessageParser;
 import eu.europa.ec.dgc.utils.CertificateUtils;
 import feign.FeignException;
@@ -158,7 +159,7 @@ boolean checkTrustAnchorSignature(TrustListItemDto trustListItem, List<X509Certi
         SignedCertificateMessageParser parser = new SignedCertificateMessageParser(
             trustListItem.getSignature(), trustListItem.getRawData());
 
-        if (parser.getParserState() != SignedCertificateMessageParser.ParserState.SUCCESS) {
+        if (parser.getParserState() != SignedMessageParser.ParserState.SUCCESS) {
             log.error("Could not parse trustListItem CMS. ParserState: {}", parser.getParserState());
             return false;
         } else if (!parser.isSignatureVerified()) {
diff --git a/src/main/java/eu/europa/ec/dgc/gateway/connector/DgcGatewayTrustedIssuerDownloadConnector.java b/src/main/java/eu/europa/ec/dgc/gateway/connector/DgcGatewayTrustedIssuerDownloadConnector.java
index 9338c17..a1fe1a3 100644
--- a/src/main/java/eu/europa/ec/dgc/gateway/connector/DgcGatewayTrustedIssuerDownloadConnector.java
+++ b/src/main/java/eu/europa/ec/dgc/gateway/connector/DgcGatewayTrustedIssuerDownloadConnector.java
@@ -92,7 +92,7 @@ public <T extends Serializable> void setQueryParameter(QueryParameter<T> queryPa
      *                       result in a list of "CSCA" and "UPLOAD" certificates with at least one matching property.
      */
     public <T extends Serializable> void setQueryParameter(QueryParameter<T> queryParameter, List<T> values) {
-        if (!queryParameter.getArrayValue() && values.size() > 1) {
+        if (Boolean.FALSE.equals(queryParameter.getArrayValue()) && values.size() > 1) {
             throw new IllegalArgumentException("Only one value is allowed for non-array query parameters.");
         }
 
diff --git a/src/test/java/eu/europa/ec/dgc/gateway/connector/TrustedIssuerDownloadConnectorTest.java b/src/test/java/eu/europa/ec/dgc/gateway/connector/TrustedIssuerDownloadConnectorTest.java
index 1f93ce7..ae3ba4d 100644
--- a/src/test/java/eu/europa/ec/dgc/gateway/connector/TrustedIssuerDownloadConnectorTest.java
+++ b/src/test/java/eu/europa/ec/dgc/gateway/connector/TrustedIssuerDownloadConnectorTest.java
@@ -21,6 +21,7 @@
 package eu.europa.ec.dgc.gateway.connector;
 
 import eu.europa.ec.dgc.gateway.connector.client.DgcGatewayConnectorRestClient;
+import eu.europa.ec.dgc.gateway.connector.model.QueryParameter;
 import eu.europa.ec.dgc.gateway.connector.model.TrustedIssuer;
 import eu.europa.ec.dgc.testdata.TrustedIssuerTestHelper;
 import feign.FeignException;
@@ -37,6 +38,7 @@
 import org.springframework.boot.test.mock.mockito.MockBean;
 import org.springframework.http.ResponseEntity;
 
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.when;
 
@@ -91,4 +93,30 @@ private Request dummyRequest() {
         return Request.create(Request.HttpMethod.GET, "url", new HashMap<>(), null, new RequestTemplate());
     }
 
+    @Test
+    void setQueryParameters() throws Exception {
+        Map<String,String> param = new HashMap<>();
+        param.put("country","DE");
+
+        when(restClientMock.downloadTrustedIssuers(param))
+            .thenReturn(ResponseEntity.ok(
+                List.of(trustedIssuerTestHelper.createTrustedIssuer("DE"))));
+
+        connector.setQueryParameter(QueryParameter.COUNTRY_CODE, "DE");
+        List<TrustedIssuer> result = connector.getTrustedIssuers();
+
+        Assertions.assertEquals(1, result.size());
+        Assertions.assertEquals("DE", result.get(0).getCountry());
+
+        connector.setQueryParameter(QueryParameter.WITH_FEDERATION, List.of(true,false));
+
+    }
+
+    @Test
+    public void setWrongQueryFormat() {
+        assertThrows(IllegalArgumentException.class, () -> {
+            connector.setQueryParameter(QueryParameter.WITH_FEDERATION, List.of(true,false));
+        });
+    }
+
 }