diff --git a/lib/optimization/dwa.cpp b/lib/optimization/dwa.cpp
index 1fbf920..8a723c1 100644
--- a/lib/optimization/dwa.cpp
+++ b/lib/optimization/dwa.cpp
@@ -99,7 +99,7 @@ double gctl::dwa::DWALoss(array<double> &g)
 
     fx_c_ = 0;
     multi_fx_ = 0.0;
-    grad_.assign_all(0.0);
+    grad_.assign(0.0);
     return fx;
 }