diff --git a/src/targetspacertrsolver.cc b/src/targetspacertrsolver.cc
index fb23d717cda28eeb39d88f01a7c71b2c8203542b..d40468b56801d5595fafa910e1947a686c6e4e75 100644
--- a/src/targetspacertrsolver.cc
+++ b/src/targetspacertrsolver.cc
@@ -16,6 +16,7 @@ setup(const AverageDistanceAssembler<TargetSpace>* assembler,
       int innerIterations,
         double innerTolerance)
 {
+    assembler_                = assembler;
     x_                        = x;
     tolerance_                = tolerance;
     maxTrustRegionSteps_      = maxTrustRegionSteps;