diff --git a/scm-webapp/src/main/java/sonia/scm/api/rest/JSONContextResolver.java b/scm-webapp/src/main/java/sonia/scm/api/rest/JSONContextResolver.java
index 1b4f41d9ab..1688e8aa0b 100644
--- a/scm-webapp/src/main/java/sonia/scm/api/rest/JSONContextResolver.java
+++ b/scm-webapp/src/main/java/sonia/scm/api/rest/JSONContextResolver.java
@@ -37,6 +37,7 @@ import com.fasterxml.jackson.databind.SerializationFeature;
 import com.fasterxml.jackson.databind.introspect.AnnotationIntrospectorPair;
 import com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector;
 import com.fasterxml.jackson.databind.type.TypeFactory;
+import com.fasterxml.jackson.databind.util.ISO8601DateFormat;
 import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
 import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 import com.fasterxml.jackson.module.jaxb.JaxbAnnotationIntrospector;
@@ -66,6 +67,7 @@ public final class JSONContextResolver implements ContextResolver<ObjectMapper>
     mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
     mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);
     mapper.configure(SerializationFeature.WRITE_DATES_WITH_ZONE_ID, true);
+    mapper.setDateFormat(new ISO8601DateFormat());
   }
   
   private AnnotationIntrospector createAnnotationIntrospector() {