diff --git a/org.eclipse.titan.designer/src/org/eclipse/titan/designer/nativewin32actions/CheckSemantic.java b/org.eclipse.titan.designer/src/org/eclipse/titan/designer/nativewin32actions/CheckSemantic.java
index ba80dbaf1146e414de23f9a3e0207ca9c23aa1c2..4325f5a09258b00c81d0dad83f68de53240b99e9 100644
--- a/org.eclipse.titan.designer/src/org/eclipse/titan/designer/nativewin32actions/CheckSemantic.java
+++ b/org.eclipse.titan.designer/src/org/eclipse/titan/designer/nativewin32actions/CheckSemantic.java
@@ -134,7 +134,7 @@ public final class CheckSemantic extends ExternalTitanAction {
 
 			String flags = TITANFlagsOptionsData.getTITANFlags(singleSelectedProject, useRuntime2);
 			if (flags != null && flags.length() > 0) {
-				command.add('-' + flags);
+				command.add(flags);
 			}
 		}