diff --git a/src/dense.cc b/src/dense.cc
index ef66756..a4e5d42 100644
--- a/src/dense.cc
+++ b/src/dense.cc
@@ -9,6 +9,8 @@
 #include "mat.hh"
 #include "subview_mat.hh"
 
+#include <armadillo>
+
 namespace php_arma
 {
     template <typename T, typename T1>
diff --git a/src/dense.hh b/src/dense.hh
index a01d87f..c1af3be 100644
--- a/src/dense.hh
+++ b/src/dense.hh
@@ -10,8 +10,6 @@
 #include "php_arma.hh"
 #include "complex.hh"
 
-#include <armadillo>
-
 #define PHP_ARMA_DENSE_OPERATOR_EX2(cls, type, func)                 \
     PHP_ARMA_OPERATOR_EX2((dense<type, cls<type>>), cls<type>, func)
 
@@ -26,6 +24,11 @@
         PHP_ARMA_DENSE_OPERATOR_EX(subview_mat, func)                \
     PHP_ARMA_OPERATOR_END()
 
+namespace arma
+{
+    template <typename T> class conv_to;
+}
+
 namespace php_arma
 {
     template <typename T, typename ChildT>
@@ -52,8 +55,9 @@ namespace php_arma
                 using n_subview_t   = typename ChildT::subview_t::native_t;
                 using dest_t        = typename ChildT::with_int_elem_t::orig_t;
                 using dest_native_t = typename dest_t::native_t;
+                using n_uint_t      = decltype(func(std::declval<n_orig_t*>(), std::declval<n_orig_t*>()).eval());
                 try {
-                    arma::umat ret;
+                    n_uint_t ret;
                     auto o1 = Z_OBJ_P(zv1);
                     auto o2 = Z_OBJ_P(zv2);
                     if (Z_OBJCE_P(zv1) == ChildT::orig_t::ce) {
diff --git a/src/php_arma.hh b/src/php_arma.hh
index 7401160..8a808d7 100644
--- a/src/php_arma.hh
+++ b/src/php_arma.hh
@@ -95,15 +95,19 @@
 #define PHP_ARMA_OPERATOR_EX(cls, func)                   \
     PHP_ARMA_OPERATOR_EX2(cls, cls, func)
 
-#define PHP_ARMA_ASSIGN_OPERATOR_EX(cls, func)            \
-    if (instanceof_function(ce, cls::ce)) {               \
-        auto v = cls::operators::func(zv1, zv2, zv1);     \
+#define PHP_ARMA_ASSIGN_OPERATOR_EX2(base, child, func)   \
+    if (instanceof_function(ce, child::ce)) {             \
+        using base_t = arg_type<void(base)>::type;        \
+        auto v = base_t::operators::func(zv1, zv2, zv1);  \
         if (rv) {                                         \
             ZVAL_COPY(rv, zv1);                           \
         }                                                 \
         return v;                                         \
     }
 
+#define PHP_ARMA_ASSIGN_OPERATOR_EX(cls, func)            \
+    PHP_ARMA_ASSIGN_OPERATOR_EX2(cls, cls, func)
+
 #endif // PHP_ARMA_OPERATORS
 
 /// Helper macros for handling native objects.
diff --git a/src/subview_mat.cc b/src/subview_mat.cc
index 2157ff9..f7f1d62 100644
--- a/src/subview_mat.cc
+++ b/src/subview_mat.cc
@@ -14,6 +14,8 @@
 #include "non_resizable_matrix.hh"
 #include "dense_non_resizable_matrix.hh"
 
+#include <armadillo>
+
 namespace php_arma
 {
     template <typename T>
diff --git a/tests/004-mat-save-load.phpt b/tests/004-mat-save-load.phpt
index fdf42ed..65f6201 100644
--- a/tests/004-mat-save-load.phpt
+++ b/tests/004-mat-save-load.phpt
@@ -17,7 +17,7 @@ require_once 'includes/assert.php';
 
 $file_name = getenv('TMP_FILE');
 
-$mat = Arma\CxDMat::fromString('(1 2) (3 4); (5 6) (7 8)');
+$mat = Arma\CxDMat::fromString('(1,2) (3,4); (5,6) (7,8)');
 batch_assert('saving of `Arma\\Mat`',
     [true, $mat->save($file_name, Arma\FileType::ARMA_BINARY)]
 );