Index: build.xml
===================================================================
--- build.xml	(revision 17476)
+++ build.xml	(working copy)
@@ -444,6 +444,7 @@
 	                    <jvmarg value="-Dfile.encoding=UTF-8"/>
 	                    <jvmarg value="-javaagent:${test.dir}/lib/jmockit.jar"/>
 	                    <jvmarg value="-Djunit.jupiter.extensions.autodetection.enabled=true"/>
+	                    <jvmarg value="-Djunit.jupiter.execution.parallel.enabled=true"/>
 	                    <jvmarg value="--add-modules" if:set="isJava9" unless:set="isJava11" />
 	                    <jvmarg value="java.activation,java.se.ee" if:set="isJava9" unless:set="isJava11" />
 	                    <jvmarg value="--add-exports" if:set="isJava9" unless:set="noJavaFX" />
Index: test/unit/org/openstreetmap/josm/gui/preferences/imagery/ImageryPreferenceTestIT.java
===================================================================
--- test/unit/org/openstreetmap/josm/gui/preferences/imagery/ImageryPreferenceTestIT.java	(revision 17476)
+++ test/unit/org/openstreetmap/josm/gui/preferences/imagery/ImageryPreferenceTestIT.java	(working copy)
@@ -29,6 +29,8 @@
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.extension.RegisterExtension;
+import org.junit.jupiter.api.parallel.Execution;
+import org.junit.jupiter.api.parallel.ExecutionMode;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
@@ -425,6 +427,7 @@
      * @param id The id of the imagery info to show as the test name
      * @param info The imagery info to test
      */
+    @Execution(ExecutionMode.CONCURRENT)
     @ParameterizedTest(name = "{0}")
     @MethodSource("data")
     void testImageryEntryValidity(String id, ImageryInfo info) {