diff --git a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/GenericRunner.kt b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/GenericRunner.kt
index b5874432..c0362ea7 100644
--- a/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/GenericRunner.kt
+++ b/modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/internal/GenericRunner.kt
@@ -146,6 +146,7 @@ abstract class GenericTestRunner: ITestRunnerContributor {
         // Default JVM args
         val jvmFlags = arrayListOf<String>().apply {
             addAll(testConfig.jvmArgs)
+            add("-ea")
             add("-classpath")
             add(classpath.map { it.jarFile.get().absolutePath }.joinToString(File.pathSeparator))
         }
diff --git a/src/test/kotlin/com/beust/kobalt/internal/DependencyTest.kt b/src/test/kotlin/com/beust/kobalt/internal/DependencyTest.kt
index 95ff078c..74db351e 100644
--- a/src/test/kotlin/com/beust/kobalt/internal/DependencyTest.kt
+++ b/src/test/kotlin/com/beust/kobalt/internal/DependencyTest.kt
@@ -50,19 +50,19 @@ class DependencyTest @Inject constructor(val context: KobaltContext) {
 
     @Test
     fun noContributorsNoInterceptors() {
-        runTest(BasePluginInfo(), listOf("-classpath", A_JAR))
+        runTest(BasePluginInfo(), listOf("-ea", "-classpath", A_JAR))
     }
 
     @Test
     fun contributorOnly() {
         runTest(BasePluginInfo().apply { testJvmFlagContributors.add(contributor) },
-                listOf("-classpath", A_JAR, "-agent", "foo"))
+                listOf("-ea", "-classpath", A_JAR, "-agent", "foo"))
     }
 
     @Test
     fun interceptorOnly() {
         runTest(BasePluginInfo().apply { testJvmFlagInterceptors.add(interceptor) },
-                listOf("-classpath", B_JAR))
+                listOf("-ea", "-classpath", B_JAR))
     }
 
     @Test
@@ -71,7 +71,7 @@ class DependencyTest @Inject constructor(val context: KobaltContext) {
                 testJvmFlagContributors.add(contributor)
                 testJvmFlagInterceptors.add(interceptor)
             },
-            listOf("-classpath", B_JAR, "-agent", "foo"))
+            listOf("-ea", "-classpath", B_JAR, "-agent", "foo"))
     }
 }