diff --git a/plugins/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/AbstractXtextTests.java b/plugins/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/AbstractXtextTests.java
index e25c12679..67bf4e65b 100644
--- a/plugins/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/AbstractXtextTests.java
+++ b/plugins/org.eclipse.xtext.junit4/src/org/eclipse/xtext/junit4/AbstractXtextTests.java
@@ -329,8 +329,9 @@ public abstract class AbstractXtextTests extends Assert implements ResourceLoadH
 		if (url == null) {
 			fail("Could not read resource: '" + filePath + "'. Is your file system case sensitive?");
 		} else {
-			if(!new File(url.getPath()).getCanonicalPath().endsWith(filePath))
-				throw new RuntimeException(filePath + ":\n" +
+			String canonicalPath = new File(new File(url.getPath()).getCanonicalPath()).toURI().getPath();
+			if(!canonicalPath.endsWith(filePath))
+				throw new RuntimeException(filePath + " -> " + canonicalPath + ":\n" +
 						"The file does not exist exactly as it was named.\n" +
 						"The test is likely to cause trouble on the build server.\n" +
 						"Is your filesystem case insensitive? Please verify the spelling.");
diff --git a/plugins/org.eclipse.xtext/src/org/eclipse/xtext/generator/JavaIoFileSystemAccess.java b/plugins/org.eclipse.xtext/src/org/eclipse/xtext/generator/JavaIoFileSystemAccess.java
index e0548fb7e..a3f27a72b 100644
--- a/plugins/org.eclipse.xtext/src/org/eclipse/xtext/generator/JavaIoFileSystemAccess.java
+++ b/plugins/org.eclipse.xtext/src/org/eclipse/xtext/generator/JavaIoFileSystemAccess.java
@@ -72,7 +72,7 @@ public class JavaIoFileSystemAccess extends AbstractFileSystemAccess {
 		if (outlet == null)
 			throw new IllegalArgumentException("A slot with name '" + outputConfigName + "' has not been configured.");
 		String pathName = toSystemFileName(outlet + "/" + fileName);
-		File file = new File(pathName);
+		File file = new File(pathName).getAbsoluteFile();
 		return file;
 	}
 
diff --git a/tests/org.eclipse.xtext.tests/src/org/eclipse/xtext/generator/JavaIoFileSystemAccessTest.java b/tests/org.eclipse.xtext.tests/src/org/eclipse/xtext/generator/JavaIoFileSystemAccessTest.java
index 005f5475e..90595db8e 100644
--- a/tests/org.eclipse.xtext.tests/src/org/eclipse/xtext/generator/JavaIoFileSystemAccessTest.java
+++ b/tests/org.eclipse.xtext.tests/src/org/eclipse/xtext/generator/JavaIoFileSystemAccessTest.java
@@ -61,7 +61,9 @@ public class JavaIoFileSystemAccessTest extends Assert {
 		JavaIoFileSystemAccess fileSystemAccess = new JavaIoFileSystemAccess();
 		fileSystemAccess.setOutputPath("testOutput", "/testDir");
 		URI uri = fileSystemAccess.getURI("testFile", "testOutput");
-		assertEquals("file:/testDir/testFile", uri.toString());
+		String expectedUri = new File(new File(File.separator + "testDir"), "testFile")
+			.toURI().toString();
+		assertEquals(expectedUri, uri.toString());
 	}
 
 	@Test
diff --git a/tests/org.eclipse.xtext.tests/src/org/eclipse/xtext/mwe/UriBasedReaderTest.java b/tests/org.eclipse.xtext.tests/src/org/eclipse/xtext/mwe/UriBasedReaderTest.java
index 413bb1954..b3479d9f8 100644
--- a/tests/org.eclipse.xtext.tests/src/org/eclipse/xtext/mwe/UriBasedReaderTest.java
+++ b/tests/org.eclipse.xtext.tests/src/org/eclipse/xtext/mwe/UriBasedReaderTest.java
@@ -7,6 +7,7 @@
  *******************************************************************************/
 package org.eclipse.xtext.mwe;
 
+import java.io.File;
 import java.util.List;
 
 import org.eclipse.emf.ecore.EPackage;
@@ -64,7 +65,7 @@ public class UriBasedReaderTest extends AbstractXtextTests {
 	@Test public void testTransitiveReferences() throws Exception {
 		UriBasedReader reader = new UriBasedReader();
 		reader.addRegister(new ImportUriTestLanguageStandaloneSetup());
-		reader.addUri("file:" + pathTo("importUriSubfolder/Start.importuritestlanguage"));
+		reader.addUri("file:/" + pathTo("importUriSubfolder/Start.importuritestlanguage"));
 
 		SlotEntry slotEntry = new SlotEntry();
 		slotEntry.setType("Type");
@@ -188,7 +189,7 @@ public class UriBasedReaderTest extends AbstractXtextTests {
 	}
 
 	public String pathTo(String string) throws Exception {
-		return new ReaderTest().pathTo(string);
+		return new ReaderTest().pathTo(string).replace(File.separator, "/");
 	}
 	
 }