diff --git a/build.gradle b/build.gradle
index dd79739ce27..2e7c14a3f76 100644
--- a/build.gradle
+++ b/build.gradle
@@ -53,10 +53,11 @@ subprojects {
     }
 
     dependencies {
-        testImplementation "org.junit.jupiter:junit-jupiter-api:5.4.0"
-        testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:5.4.0"
-        testImplementation "org.junit.jupiter:junit-jupiter-params:5.4.0"
+        testImplementation "org.junit.jupiter:junit-jupiter-api:5.10.0"
+        testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:5.10.0"
+        testImplementation "org.junit.jupiter:junit-jupiter-params:5.10.0"
         testImplementation "org.hamcrest:hamcrest:2.1"
+        testCompileOnly "org.apiguardian:apiguardian-api:1.1.2"
     }
 
     // Reusable license copySpec for building JARs
diff --git a/smithy-cli/build.gradle b/smithy-cli/build.gradle
index df4bd77d0ca..dcfb805adb7 100644
--- a/smithy-cli/build.gradle
+++ b/smithy-cli/build.gradle
@@ -57,6 +57,7 @@ dependencies {
     implementation "org.slf4j:slf4j-jdk14:1.7.36" // Route slf4j used by Maven through JUL like the rest of Smithy.
 
     testImplementation "org.mock-server:mockserver-netty:3.10.8"
+
 }
 
 // ------ Shade Maven dependency resolvers into the JAR. -------
@@ -223,7 +224,7 @@ tasks["runtime"].dependsOn("shadowJar")
 
 sourceSets {
     create("it") {
-        compileClasspath += sourceSets["main"].output + configurations["testRuntimeClasspath"]
+        compileClasspath += sourceSets["main"].output + configurations["testRuntimeClasspath"] + configurations["testCompileClasspath"]
         runtimeClasspath += output + compileClasspath + sourceSets["test"].runtimeClasspath
     }
 }
@@ -233,7 +234,11 @@ task integ(type: Test) {
     systemProperty "SMITHY_BINARY", "${smithyBinary}"
     testClassesDirs = sourceSets["it"].output.classesDirs
     classpath = sourceSets["it"].runtimeClasspath
-    maxParallelForks = Runtime.getRuntime().availableProcessors() / 2
+
+    // Configuration parameters to execute top-level classes in parallel but methods in same thread
+    systemProperties["junit.jupiter.execution.parallel.enabled"] = "true"
+    systemProperties["junit.jupiter.execution.parallel.mode.default"] = "same_thread"
+    systemProperties["junit.jupiter.execution.parallel.mode.classes.default"] = "concurrent"
 
     testLogging {
         events = ["passed", "skipped", "failed"]
diff --git a/smithy-cli/src/it/java/software/amazon/smithy/cli/CleanCommandTest.java b/smithy-cli/src/it/java/software/amazon/smithy/cli/CleanCommandTest.java
index 29fb1da6e62..a2ef93611fb 100644
--- a/smithy-cli/src/it/java/software/amazon/smithy/cli/CleanCommandTest.java
+++ b/smithy-cli/src/it/java/software/amazon/smithy/cli/CleanCommandTest.java
@@ -11,13 +11,13 @@
 import java.io.UncheckedIOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.parallel.Isolated;
 import software.amazon.smithy.utils.IoUtils;
 import software.amazon.smithy.utils.ListUtils;
 
-
+@Isolated
 public class CleanCommandTest {
     private static final String PROJECT_NAME = "simple-config-sources";
     @Test
diff --git a/smithy-cli/src/it/java/software/amazon/smithy/cli/InitCommandTest.java b/smithy-cli/src/it/java/software/amazon/smithy/cli/InitCommandTest.java
index 102a97993af..ae8aef6364a 100644
--- a/smithy-cli/src/it/java/software/amazon/smithy/cli/InitCommandTest.java
+++ b/smithy-cli/src/it/java/software/amazon/smithy/cli/InitCommandTest.java
@@ -10,6 +10,7 @@
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.parallel.Isolated;
 import software.amazon.smithy.utils.IoUtils;
 import software.amazon.smithy.utils.ListUtils;
 
@@ -20,6 +21,7 @@
 import java.util.Collections;
 import java.util.List;
 
+@Isolated
 public class InitCommandTest {
     private static final String PROJECT_NAME = "smithy-templates";