diff --git a/memcheck.R b/memcheck.R
index a427f729..3d6c54d5 100644
--- a/memcheck.R
+++ b/memcheck.R
@@ -1,5 +1,8 @@
 devtools::load_all()
 library(testthat)
+
+# Test the c++ functions, which can all be done using sim_mvgam()
+# and forecast()
 capture_output(sim_mvgam(family = gaussian(),
                          trend_model = RW()))
 capture_output(sim_mvgam(family = gaussian(),
@@ -12,3 +15,5 @@ capture_output(sim_mvgam(family = gaussian(),
                          trend_model = VAR()))
 capture_output(sim_mvgam(family = gaussian(),
                          trend_model = VAR(cor = TRUE)))
+fc <- forecast(mvgam:::mvgam_example1,
+               newdata = mvgam:::mvgam_examp_dat$data_test)
diff --git a/src/mvgam.dll b/src/mvgam.dll
index 860343be..df036f39 100644
Binary files a/src/mvgam.dll and b/src/mvgam.dll differ
diff --git a/src/trend_funs.cpp b/src/trend_funs.cpp
index fe31d4c0..8e4e30c2 100644
--- a/src/trend_funs.cpp
+++ b/src/trend_funs.cpp
@@ -16,17 +16,17 @@ Rcpp::NumericVector ar3_recursC(double drift, double ar1,
 
   int T = h + 3;
   Rcpp::NumericVector states(T);
-  states[0] = last_trends[0];
-  states[1] = last_trends[1];
-  states[2] = last_trends[2];
+  states(0) = last_trends(0);
+  states(1) = last_trends(1);
+  states(2) = last_trends(2);
 
   for(int t = 3; t < T; ++t) {
-    states[t] = drift +
-      ar1 * (states[t - 1] - linpreds[t - 1]) +
-      ar2 * (states[t - 2] - linpreds[t - 2]) +
-      ar3 * (states[t - 3] - linpreds[t - 3]) +
-      linpreds[t]  +
-      errors[t];
+    states(t) = drift +
+      ar1 * (states(t - 1) - linpreds(t - 1)) +
+      ar2 * (states(t - 2) - linpreds(t - 2)) +
+      ar3 * (states(t - 3) - linpreds(t - 3)) +
+      linpreds(t)  +
+      errors(t);
   }
   return states[Rcpp::Range(3, T-1)];
 }
diff --git a/src/trend_funs.o b/src/trend_funs.o
index 5b5854bc..917270cf 100644
Binary files a/src/trend_funs.o and b/src/trend_funs.o differ