diff --git a/lib/algorithms/iterative/FlexibleGeneralisedMinimalResidual.h b/lib/algorithms/iterative/FlexibleGeneralisedMinimalResidual.h
index 3e677a77..94193484 100644
--- a/lib/algorithms/iterative/FlexibleGeneralisedMinimalResidual.h
+++ b/lib/algorithms/iterative/FlexibleGeneralisedMinimalResidual.h
@@ -174,7 +174,7 @@ class FlexibleGeneralisedMinimalResidual : public OperatorFunction<Field> {
     MatrixTimer.Stop();
 
     PrecTimer.Start();
-    Preconditioner(z, r);
+    Preconditioner(z, w);
     PrecTimer.Stop();
 
     LinalgTimer.Start();