diff --git a/matlab/csolve.m b/matlab/csolve.m
index 8bcb81f2663044e0151d9ecfa670f425b9f05f19..3af47243ebc107c391d37c31ac93c1fa7dc8055b 100644
--- a/matlab/csolve.m
+++ b/matlab/csolve.m
@@ -84,7 +84,7 @@ while ~done
             [f0,grad] = feval(gradfun,x,varargin{:});
         end
         if isreal(grad)
-            if rcond(grad)<1e-12
+            if rcond(full(grad))<1e-12
                 grad=grad+tvec;
             end
             dx0=-grad\f0;