diff --git a/core/src/testFixtures/java/org/lflang/tests/LFTest.java b/core/src/testFixtures/java/org/lflang/tests/LFTest.java
index e99fee4b54..1fa4184237 100644
--- a/core/src/testFixtures/java/org/lflang/tests/LFTest.java
+++ b/core/src/testFixtures/java/org/lflang/tests/LFTest.java
@@ -39,6 +39,12 @@ public class LFTest implements Comparable<LFTest> {
   /** String builder for collecting issues encountered during test execution. */
   private final StringBuilder issues = new StringBuilder();
 
+  /** Reference to System.out for restoring the default output. */
+  private static final PrintStream out = System.out;
+
+  /** Reference to System.err for restoring the default output. */
+  private static final PrintStream err = System.err;
+
   private long executionTimeNanoseconds;
 
   /**
@@ -71,11 +77,11 @@ public void redirectOutputs() {
   }
 
   /** End output redirection. */
-  public void restoreOutputs() {
+  public static void restoreOutputs() {
     System.out.flush();
     System.err.flush();
-    System.setOut(System.out);
-    System.setErr(System.err);
+    System.setOut(out);
+    System.setErr(err);
   }
 
   /**
@@ -130,7 +136,7 @@ public boolean hasPassed() {
     return result == Result.TEST_PASS;
   }
 
-  /** Compile a string that contains all collected errors and return it. */
+  /** Print a report of all the collected errors. */
   public void reportErrors() {
     if (this.hasFailed()) {
       System.out.println(
diff --git a/core/src/testFixtures/java/org/lflang/tests/TestBase.java b/core/src/testFixtures/java/org/lflang/tests/TestBase.java
index ee0d72ff02..04a699068c 100644
--- a/core/src/testFixtures/java/org/lflang/tests/TestBase.java
+++ b/core/src/testFixtures/java/org/lflang/tests/TestBase.java
@@ -328,7 +328,7 @@ private static void checkAndReportFailures(Set<LFTest> tests) {
     var passed = tests.stream().filter(LFTest::hasPassed).toList();
     var s = new StringBuffer();
     s.append(THIN_LINE);
-    s.append("Passing: ").append(passed.size()).append("/").append(tests.size()).append("%n");
+    s.append(String.format("Passing: %d/%d%n", passed.size(), tests.size()));
     s.append(THIN_LINE);
     passed.forEach(
         test ->