diff --git a/Mustang-CLI/pom.xml b/Mustang-CLI/pom.xml
index 3a2ae520..22f41162 100644
--- a/Mustang-CLI/pom.xml
+++ b/Mustang-CLI/pom.xml
@@ -106,8 +106,10 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.5.3</version>
                 <configuration>
                     <runOrder>alphabetical</runOrder>
+                    <argLine>-Duser.timezone=UTC</argLine>
                 </configuration>
             </plugin>
             <!-- allow getImplementationVersion for the pom.xml -->
diff --git a/library/pom.xml b/library/pom.xml
index 55bf65f5..10442661 100644
--- a/library/pom.xml
+++ b/library/pom.xml
@@ -179,8 +179,10 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.5.3</version>
                 <configuration>
                     <runOrder>alphabetical</runOrder>
+                    <argLine>-Duser.timezone=UTC</argLine>
                 </configuration>
             </plugin>
             <plugin>
diff --git a/library/src/test/java/org/mustangproject/ZUGFeRD/DeSerializationTest.java b/library/src/test/java/org/mustangproject/ZUGFeRD/DeSerializationTest.java
index c0ac9f3a..368afcc8 100644
--- a/library/src/test/java/org/mustangproject/ZUGFeRD/DeSerializationTest.java
+++ b/library/src/test/java/org/mustangproject/ZUGFeRD/DeSerializationTest.java
@@ -461,8 +461,8 @@ public class DeSerializationTest extends ResourceCase {
 		assertEquals(globalID, fromJSON.getSender().getGlobalID());
 		assertEquals(globalIDScheme, fromJSON.getSender().getGlobalIDScheme());
 		SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
-		assertEquals("2022-01-29", sdf.format(fromJSON.getZFItems()[0].getDetailedDeliveryPeriodFrom()));
-		assertEquals("2022-01-31", sdf.format(fromJSON.getZFItems()[0].getDetailedDeliveryPeriodTo()));
+		assertEquals("2022-01-28", sdf.format(fromJSON.getZFItems()[0].getDetailedDeliveryPeriodFrom()));
+		assertEquals("2022-01-30", sdf.format(fromJSON.getZFItems()[0].getDetailedDeliveryPeriodTo()));
 		assertEquals("sender@test.org", fromJSON.getSender().getEmail());
 	}
 
diff --git a/library/src/test/java/org/mustangproject/ZUGFeRD/ZF2ZInvoiceImporterTest.java b/library/src/test/java/org/mustangproject/ZUGFeRD/ZF2ZInvoiceImporterTest.java
index 966859f8..47ac24cb 100644
--- a/library/src/test/java/org/mustangproject/ZUGFeRD/ZF2ZInvoiceImporterTest.java
+++ b/library/src/test/java/org/mustangproject/ZUGFeRD/ZF2ZInvoiceImporterTest.java
@@ -407,7 +407,7 @@ public class ZF2ZInvoiceImporterTest extends ResourceCase {
 			ObjectMapper mapper = new ObjectMapper();
 
 			String jsonArray = mapper.writeValueAsString(i);
-			JSONAssert.assertEquals("{\"documentCode\":\"380\",\"number\":\"471102\",\"currency\":\"EUR\",\"paymentTermDescription\":\"Der Betrag in Höhe von EUR 529,87 wird am 20.03.2018 von Ihrem Konto per SEPA-Lastschrift eingezogen.\\n          \",\"issueDate\":1520118000000,\"deliveryDate\":1520118000000,\"sender\":{\"name\":\"Lieferant GmbH\",\"zip\":\"80333\",\"street\":\"Lieferantenstraße 20\",\"location\":\"München\",\"country\":\"DE\",\"taxID\":\"201/113/40209\",\"vatID\":\"DE123456789\",\"debitDetails\":[{\"mandate\":\"REF A-123\",\"paymentMeansCode\":\"59\",\"paymentMeansInformation\":\"SEPA direct debit\",\"iban\":\"DE21860000000086001055\"}],\"vatid\":\"DE123456789\"},\"recipient\":{\"name\":\"Kunden AG Mitte\",\"zip\":\"69876\",\"street\":\"Kundenstraße 15\",\"location\":\"Frankfurt\",\"country\":\"DE\",\"bankDetails\":[{\"paymentMeansCode\":\"58\",\"paymentMeansInformation\":\"SEPA credit transfer\",\"iban\":\"DE21860000000086001055\"}]},\"totalPrepaidAmount\":0.00,\"creditorReferenceID\":\"DE98ZZZ09999999999\",\"valid\":false,\"zfitems\":[{\"price\":9.9000,\"quantity\":20.0000,\"basisQuantity\":1.0000,\"id\":\"1\",\"product\":{\"unit\":\"H87\",\"name\":\"Trennblätter A4\",\"taxCategoryCode\":\"S\",\"vatpercent\":19.00,\"reverseCharge\":false,\"intraCommunitySupply\":false},\"value\":9.9000},{\"price\":5.5000,\"quantity\":50.0000,\"basisQuantity\":1.0000,\"id\":\"2\",\"product\":{\"unit\":\"H87\",\"name\":\"Joghurt Banane\",\"taxCategoryCode\":\"S\",\"vatpercent\":7.00,\"reverseCharge\":false,\"intraCommunitySupply\":false},\"value\":5.5000}],\"tradeSettlement\":[{\"mandate\":\"REF A-123\",\"paymentMeansCode\":\"59\",\"paymentMeansInformation\":\"SEPA direct debit\",\"iban\":\"DE21860000000086001055\"}],\"ownTaxID\":\"201/113/40209\",\"ownZIP\":\"80333\",\"ownCountry\":\"DE\",\"ownVATID\":\"DE123456789\",\"ownLocation\":\"München\",\"ownStreet\":\"Lieferantenstraße 20\"}",jsonArray,false);
+			JSONAssert.assertEquals("{\"documentCode\":\"380\",\"number\":\"471102\",\"currency\":\"EUR\",\"paymentTermDescription\":\"Der Betrag in Höhe von EUR 529,87 wird am 20.03.2018 von Ihrem Konto per SEPA-Lastschrift eingezogen.\\n          \",\"issueDate\":1520121600000,\"deliveryDate\":1520121600000,\"sender\":{\"name\":\"Lieferant GmbH\",\"zip\":\"80333\",\"street\":\"Lieferantenstraße 20\",\"location\":\"München\",\"country\":\"DE\",\"taxID\":\"201/113/40209\",\"vatID\":\"DE123456789\",\"debitDetails\":[{\"mandate\":\"REF A-123\",\"paymentMeansCode\":\"59\",\"paymentMeansInformation\":\"SEPA direct debit\",\"iban\":\"DE21860000000086001055\"}],\"vatid\":\"DE123456789\"},\"recipient\":{\"name\":\"Kunden AG Mitte\",\"zip\":\"69876\",\"street\":\"Kundenstraße 15\",\"location\":\"Frankfurt\",\"country\":\"DE\",\"bankDetails\":[{\"paymentMeansCode\":\"58\",\"paymentMeansInformation\":\"SEPA credit transfer\",\"iban\":\"DE21860000000086001055\"}]},\"totalPrepaidAmount\":0.00,\"creditorReferenceID\":\"DE98ZZZ09999999999\",\"valid\":false,\"zfitems\":[{\"price\":9.9000,\"quantity\":20.0000,\"basisQuantity\":1.0000,\"id\":\"1\",\"product\":{\"unit\":\"H87\",\"name\":\"Trennblätter A4\",\"taxCategoryCode\":\"S\",\"vatpercent\":19.00,\"reverseCharge\":false,\"intraCommunitySupply\":false},\"value\":9.9000},{\"price\":5.5000,\"quantity\":50.0000,\"basisQuantity\":1.0000,\"id\":\"2\",\"product\":{\"unit\":\"H87\",\"name\":\"Joghurt Banane\",\"taxCategoryCode\":\"S\",\"vatpercent\":7.00,\"reverseCharge\":false,\"intraCommunitySupply\":false},\"value\":5.5000}],\"tradeSettlement\":[{\"mandate\":\"REF A-123\",\"paymentMeansCode\":\"59\",\"paymentMeansInformation\":\"SEPA direct debit\",\"iban\":\"DE21860000000086001055\"}],\"ownTaxID\":\"201/113/40209\",\"ownZIP\":\"80333\",\"ownCountry\":\"DE\",\"ownVATID\":\"DE123456789\",\"ownLocation\":\"München\",\"ownStreet\":\"Lieferantenstraße 20\"}",jsonArray,false);
 
 		} catch (IOException e) {
 			fail("IOException not expected");
@@ -418,7 +418,7 @@ public class ZF2ZInvoiceImporterTest extends ResourceCase {
 		}
 	}
 	public static Date atStartOfDay(Date date) {
-		ZoneId tz=ZoneId.ofOffset("GMT", ZoneOffset.ofHours(+2));
+		ZoneId tz=ZoneId.ofOffset("UTC", ZoneOffset.ofHours(0));
 		LocalDateTime localDateTime = LocalDateTime.ofInstant(date.toInstant(), tz);
 		LocalDateTime startOfDay = localDateTime.with(LocalTime.MIN);
 		return Date.from(startOfDay.atZone(tz).toInstant());
diff --git a/pom.xml b/pom.xml
index 52b863b8..b5c94c61 100644
--- a/pom.xml
+++ b/pom.xml
@@ -81,17 +81,16 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.5.3</version>
                 <configuration>
                     <runOrder>alphabetical</runOrder>
+                    <argLine>-Duser.timezone=UTC</argLine>
                 </configuration>
             </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-source-plugin</artifactId>
-                <version>3.2.1</version>
-                <configuration>
-                    <encoding>UTF-8</encoding>
-                </configuration>
+                <version>3.3.1</version>
                 <executions>
                     <execution>
                         <id>attach-javadoc</id>
diff --git a/validator/pom.xml b/validator/pom.xml
index f5b5281a..57866cba 100644
--- a/validator/pom.xml
+++ b/validator/pom.xml
@@ -129,8 +129,10 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.5.3</version>
                 <configuration>
                     <runOrder>alphabetical</runOrder>
+                    <argLine>-Duser.timezone=UTC</argLine>
                 </configuration>
             </plugin>
             <!-- allow getImplementationVersion for the pom.xml -->