diff --git a/org.eclipse.jgit.lfs.server.test/tst/org/eclipse/jgit/lfs/server/fs/LfsServerTest.java b/org.eclipse.jgit.lfs.server.test/tst/org/eclipse/jgit/lfs/server/fs/LfsServerTest.java
index ec44da4ca..e55c4c643 100644
--- a/org.eclipse.jgit.lfs.server.test/tst/org/eclipse/jgit/lfs/server/fs/LfsServerTest.java
+++ b/org.eclipse.jgit.lfs.server.test/tst/org/eclipse/jgit/lfs/server/fs/LfsServerTest.java
@@ -74,6 +74,7 @@ import org.apache.http.impl.client.CloseableHttpClient;
 import org.apache.http.impl.client.HttpClientBuilder;
 import org.eclipse.jetty.servlet.ServletContextHandler;
 import org.eclipse.jetty.servlet.ServletHolder;
+import org.eclipse.jgit.junit.MockSystemReader;
 import org.eclipse.jgit.junit.http.AppServer;
 import org.eclipse.jgit.lfs.errors.LfsException;
 import org.eclipse.jgit.lfs.lib.AnyLongObjectId;
@@ -85,6 +86,7 @@ import org.eclipse.jgit.lfs.test.LongObjectIdTestUtils;
 import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.FileUtils;
 import org.eclipse.jgit.util.IO;
+import org.eclipse.jgit.util.SystemReader;
 import org.junit.After;
 import org.junit.Before;
 
@@ -119,6 +121,7 @@ public abstract class LfsServerTest {
 
 	@Before
 	public void setup() throws Exception {
+		SystemReader.setInstance(new MockSystemReader());
 		tmp = Files.createTempDirectory("jgit_test_");
 
 		// measure timer resolution before the test to avoid time critical tests
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/FileSnapshotTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/FileSnapshotTest.java
index 6fa35d64b..35f4fcba9 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/FileSnapshotTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/FileSnapshotTest.java
@@ -62,6 +62,7 @@ import java.time.Instant;
 import java.util.ArrayList;
 import java.util.concurrent.TimeUnit;
 
+import org.eclipse.jgit.junit.MockSystemReader;
 import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.FS.FileStoreAttributes;
 import org.eclipse.jgit.util.FileUtils;
@@ -84,6 +85,7 @@ public class FileSnapshotTest {
 
 	@Before
 	public void setUp() throws Exception {
+		SystemReader.setInstance(new MockSystemReader());
 		trash = Files.createTempDirectory("tmp_");
 		// measure timer resolution before the test to avoid time critical tests
 		// are affected by time needed for measurement
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/FileBasedConfigTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/FileBasedConfigTest.java
index 1adddb5ea..f3cd61da6 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/FileBasedConfigTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/storage/file/FileBasedConfigTest.java
@@ -55,9 +55,11 @@ import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
 
 import org.eclipse.jgit.errors.ConfigInvalidException;
+import org.eclipse.jgit.junit.MockSystemReader;
 import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.FileUtils;
 import org.eclipse.jgit.util.IO;
+import org.eclipse.jgit.util.SystemReader;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -82,6 +84,7 @@ public class FileBasedConfigTest {
 
 	@Before
 	public void setUp() throws Exception {
+		SystemReader.setInstance(new MockSystemReader());
 		trash = Files.createTempDirectory("tmp_");
 		FS.getFileStoreAttributes(trash.getParent());
 	}