diff --git a/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java
index b0a1827265e6f04602957f700bd951c37debe5e9..bf236ab17d5d663e696ba3cf342dd7d3bd5b9f9c 100644
--- a/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java
+++ b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/MockSystemReader.java
@@ -251,7 +251,7 @@ public TimeZone getTimeZone() {
 
 	@Override
 	public ZoneId getTimeZoneId() {
-		return ZoneOffset.ofHoursMinutes(-3, 30);
+		return ZoneOffset.ofHoursMinutes(-3, -30);
 	}
 
 	@Override