diff --git a/headless-services/commons/language-server-test-harness/src/main/java/org/springframework/ide/vscode/languageserver/testharness/LanguageServerHarness.java b/headless-services/commons/language-server-test-harness/src/main/java/org/springframework/ide/vscode/languageserver/testharness/LanguageServerHarness.java
index 719408b41..296e848d5 100644
--- a/headless-services/commons/language-server-test-harness/src/main/java/org/springframework/ide/vscode/languageserver/testharness/LanguageServerHarness.java
+++ b/headless-services/commons/language-server-test-harness/src/main/java/org/springframework/ide/vscode/languageserver/testharness/LanguageServerHarness.java
@@ -145,7 +145,7 @@ public class LanguageServerHarness<S extends SimpleLanguageServerWrapper> {
 		this.defaultLanguageId = defaultLanguageId;
 	}
 
-	public static final Duration HIGHLIGHTS_TIMEOUT = Duration.ofMillis(10_000); //Why so long?
+	public static final Duration HIGHLIGHTS_TIMEOUT = Duration.ofMillis(15_000); //Why so long?
 
 	public LanguageServerHarness(Callable<S> factory) throws Exception {
 		this(factory, LanguageId.PLAINTEXT);