diff --git a/R/gdistsamp.R b/R/gdistsamp.R
index c43076a8..f021c90f 100644
--- a/R/gdistsamp.R
+++ b/R/gdistsamp.R
@@ -399,8 +399,9 @@ if(engine =="C"){
     as.vector(t(out))
   }
   y_long <- long_format(y)
-  kmytC <- kmyt
-  kmytC[which(is.na(kmyt))] <- 0
+  # Vectorize these arrays as using arma::subcube sometimes crashes
+  kmytC <- as.vector(aperm(kmyt, c(3,2,1)))
+  lfac.kmytC <- as.vector(aperm(lfac.kmyt, c(3,2,1)))
   if(output!='density'){
     A <- rep(1, M)
   }
@@ -411,7 +412,7 @@ if(engine =="C"){
   nll <- function(params){
     nll_gdistsamp(params, n_param, y_long, mixture_code, keyfun, survey,
                   Xlam, Xlam.offset, A, Xphi, Xphi.offset, Xdet, Xdet.offset,
-                  db, a, t(u), w, k, lfac.k, lfac.kmyt, kmyt, Kmin, threads)
+                  db, a, t(u), w, k, lfac.k, lfac.kmytC, kmytC, Kmin, threads)
   }
 
 } else {
diff --git a/src/RcppExports.cpp b/src/RcppExports.cpp
index 0fe45a8a..455bc52c 100644
--- a/src/RcppExports.cpp
+++ b/src/RcppExports.cpp
@@ -141,7 +141,7 @@ BEGIN_RCPP
 END_RCPP
 }
 // nll_gdistsamp
-double nll_gdistsamp(arma::vec beta, arma::uvec n_param, arma::vec y, int mixture, std::string keyfun, std::string survey, arma::mat Xlam, arma::vec Xlam_offset, arma::vec A, arma::mat Xphi, arma::vec Xphi_offset, arma::mat Xdet, arma::vec Xdet_offset, arma::vec db, arma::mat a, arma::mat u, arma::vec w, arma::vec k, arma::vec lfac_k, arma::cube lfac_kmyt, arma::cube kmyt, arma::uvec Kmin, int threads);
+double nll_gdistsamp(arma::vec beta, arma::uvec n_param, arma::vec y, int mixture, std::string keyfun, std::string survey, arma::mat Xlam, arma::vec Xlam_offset, arma::vec A, arma::mat Xphi, arma::vec Xphi_offset, arma::mat Xdet, arma::vec Xdet_offset, arma::vec db, arma::mat a, arma::mat u, arma::vec w, arma::vec k, arma::vec lfac_k, arma::vec lfac_kmyt, arma::vec kmyt, arma::uvec Kmin, int threads);
 RcppExport SEXP _unmarked_nll_gdistsamp(SEXP betaSEXP, SEXP n_paramSEXP, SEXP ySEXP, SEXP mixtureSEXP, SEXP keyfunSEXP, SEXP surveySEXP, SEXP XlamSEXP, SEXP Xlam_offsetSEXP, SEXP ASEXP, SEXP XphiSEXP, SEXP Xphi_offsetSEXP, SEXP XdetSEXP, SEXP Xdet_offsetSEXP, SEXP dbSEXP, SEXP aSEXP, SEXP uSEXP, SEXP wSEXP, SEXP kSEXP, SEXP lfac_kSEXP, SEXP lfac_kmytSEXP, SEXP kmytSEXP, SEXP KminSEXP, SEXP threadsSEXP) {
 BEGIN_RCPP
     Rcpp::RObject rcpp_result_gen;
@@ -165,8 +165,8 @@ BEGIN_RCPP
     Rcpp::traits::input_parameter< arma::vec >::type w(wSEXP);
     Rcpp::traits::input_parameter< arma::vec >::type k(kSEXP);
     Rcpp::traits::input_parameter< arma::vec >::type lfac_k(lfac_kSEXP);
-    Rcpp::traits::input_parameter< arma::cube >::type lfac_kmyt(lfac_kmytSEXP);
-    Rcpp::traits::input_parameter< arma::cube >::type kmyt(kmytSEXP);
+    Rcpp::traits::input_parameter< arma::vec >::type lfac_kmyt(lfac_kmytSEXP);
+    Rcpp::traits::input_parameter< arma::vec >::type kmyt(kmytSEXP);
     Rcpp::traits::input_parameter< arma::uvec >::type Kmin(KminSEXP);
     Rcpp::traits::input_parameter< int >::type threads(threadsSEXP);
     rcpp_result_gen = Rcpp::wrap(nll_gdistsamp(beta, n_param, y, mixture, keyfun, survey, Xlam, Xlam_offset, A, Xphi, Xphi_offset, Xdet, Xdet_offset, db, a, u, w, k, lfac_k, lfac_kmyt, kmyt, Kmin, threads));
diff --git a/src/nll_gdistsamp.cpp b/src/nll_gdistsamp.cpp
index 80dc2d45..2ae91331 100644
--- a/src/nll_gdistsamp.cpp
+++ b/src/nll_gdistsamp.cpp
@@ -17,7 +17,7 @@ double nll_gdistsamp(arma::vec beta, arma::uvec n_param, arma::vec y,
     arma::mat Xlam, arma::vec Xlam_offset, arma::vec A, arma::mat Xphi,
     arma::vec Xphi_offset, arma::mat Xdet, arma::vec Xdet_offset, arma::vec db,
     arma::mat a, arma::mat u, arma::vec w, arma::vec k, arma::vec lfac_k,
-    arma::cube lfac_kmyt, arma::cube kmyt, arma::uvec Kmin, int threads){
+    arma::vec lfac_kmyt, arma::vec kmyt, arma::uvec Kmin, int threads){
 
   #ifdef _OPENMP
     omp_set_num_threads(threads);
@@ -27,7 +27,8 @@ double nll_gdistsamp(arma::vec beta, arma::uvec n_param, arma::vec y,
   int T = Xphi.n_rows / M;
   int R = y.size() / M;
   unsigned J = R / T;
-  int K = k.size() - 1;
+  int lk = k.size();
+  int K = lk - 1;
 
   //Abundance
   const vec lambda = exp(Xlam * beta_sub(beta, n_param, 0) + Xlam_offset) % A;
@@ -53,9 +54,18 @@ double nll_gdistsamp(arma::vec beta, arma::uvec n_param, arma::vec y,
 
     int t_ind = i * T;
     int y_ind = i * T * J;
+    int k_start = i * T * lk;
 
     vec y_sub(J);
-
+    vec p(J);
+    vec p1(lk);
+    vec p3(J);
+    vec p4(lk);
+    double p5;
+
+    //Some unnecessary calculations here when k < Kmin
+    //These values are ignored later in calculation of site_lp
+    //However hard to avoid without refactoring entirely I think
     mat mn = zeros(K+1, T);
     for(int t=0; t<T; t++){
       int y_stop = y_ind + J - 1;
@@ -64,23 +74,27 @@ double nll_gdistsamp(arma::vec beta, arma::uvec n_param, arma::vec y,
 
       if(not_missing.size() == J){
 
-        vec p1 = lfac_kmyt.subcube(span(i),span(t),span());
-        vec p = distprob(keyfun, det_param(t_ind), scale, survey, db,
+        int k_stop = k_start + lk - 1;
+
+        p1 = lfac_kmyt.subvec(k_start, k_stop);
+
+        p = distprob(keyfun, det_param(t_ind), scale, survey, db,
                           w, a.row(i));
-        vec p3 = p % u.col(i) * phi(t_ind);
-        //the following line causes a segfault only in R CMD check,
-        //when kmyt contains NA values
-        vec p4 = kmyt.subcube(span(i),span(t),span());
+        p3 = p % u.col(i) * phi(t_ind);
+
+        p4 = kmyt.subvec(k_start, k_stop);
 
-        double p5 = 1 - sum(p3);
+        p5 = 1 - sum(p3);
 
         mn.col(t) = lfac_k - p1 + sum(y_sub % log(p3)) + p4 * log(p5);
       }
 
       t_ind += 1;
       y_ind += J;
+      k_start += lk;
     }
 
+    //Note that rows of mn for k < Kmin are skipped here
     double site_lp = 0.0;
     for (int j=Kmin(i); j<(K+1); j++){
       site_lp += N_density(mixture, j, lambda(i), log_alpha) *