diff --git a/.travis.yml b/.travis.yml
index baa63f94..43a28c63 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -97,6 +97,7 @@ install:
     fi
 
 script:
+  - python doc/extract_code.py
   - cd build
   - if [ "${CMAKE_BUILD_TYPE}" = "cov" ]; then
 
@@ -120,7 +121,6 @@ script:
       make -j2 &&
       ctest -V;
     else
-      python ../doc/extract_code.py;
       cmake . -DBOOST_ROOT=${BOOST_DIR}
               -DBUILD_PYTHON=${BUILD_PYTHON}
               -DPYTHON_VERSION=${PYTHON_VERSION}
diff --git a/src/python/histogram.cpp b/src/python/histogram.cpp
index 4ee39106..d27ed3c1 100644
--- a/src/python/histogram.cpp
+++ b/src/python/histogram.cpp
@@ -43,31 +43,27 @@ public:
   template <typename T>
   using array = histogram::adaptive_storage<>::array<T>;
 
-  struct dtype_visitor : public static_visitor<std::pair<int, object>> {
+  struct dtype_visitor : public static_visitor<str> {
+    list & shapes, & strides;
+    dtype_visitor(list &sh, list &st) : shapes(sh), strides(st) {}
     template <typename Array>
-    std::pair<int, object> operator()(const Array& /*unused*/) const {
-      std::pair<int, object> p;
-      p.first = sizeof(typename Array::value_type);
-      p.second = dtype_typestr<typename Array::value_type>();
-      return p;
+    str operator()(const Array& /*unused*/) const {
+      strides.append(sizeof(typename Array::value_type));
+      return dtype_typestr<typename Array::value_type>();
     }
-    std::pair<int, object> operator()(const array<void>& /*unused*/) const {
-      std::pair<int, object> p;
-      p.first = sizeof(uint8_t);
-      p.second = dtype_typestr<uint8_t>();
-      return p;
+    str operator()(const array<void>& /*unused*/) const {
+      strides.append(sizeof(uint8_t));
+      return dtype_typestr<uint8_t>();
     }
-    std::pair<int, object> operator()(const array<mp_int>& /*unused*/) const {
-      std::pair<int, object> p;
-      p.first = sizeof(double);
-      p.second = dtype_typestr<double>();
-      return p;
+    str operator()(const array<mp_int>& /*unused*/) const {
+      strides.append(sizeof(double));
+      return dtype_typestr<double>();
     }
-    std::pair<int, object> operator()(const array<weight>& /*unused*/) const {
-      std::pair<int, object> p;
-      p.first = 0; // communicate that the type was array<weight>
-      p.second = dtype_typestr<double>();
-      return p;
+    str operator()(const array<weight>& /*unused*/) const {
+      strides.append(sizeof(double));
+      strides.append(strides[-1] * 2);
+      shapes.append(2);
+      return dtype_typestr<double>();
     }
   };
 
@@ -119,31 +115,18 @@ public:
 
   static object array_interface(const histogram::dynamic_histogram &self) {
     dict d;
-
     list shapes;
     list strides;
     auto &b = self.storage_.buffer_;
-    auto dtype = apply_visitor(dtype_visitor(), b);
-    auto stride = dtype.first;
-    if (stride == 0) { // buffer is weight, needs special treatment
-      stride = sizeof(double);
-      strides.append(stride);
-      stride *= 2;
-      shapes.append(2);
-    }
+    d["typestr"] = apply_visitor(dtype_visitor(shapes, strides), b);
     for (unsigned i = 0; i < self.dim(); ++i) {
-      const auto s = histogram::shape(self.axis(i));
-      shapes.append(s);
-      strides.append(stride);
-      stride *= s;
+      if (i) strides.append(strides[-1] * shapes[-1]);
+      shapes.append(histogram::shape(self.axis(i)));
     }
-    if (self.dim() == 0) {
+    if (self.dim() == 0)
       shapes.append(0);
-      strides.append(stride);
-    }
     d["shape"] = tuple(shapes);
     d["strides"] = tuple(strides);
-    d["typestr"] = dtype.second;
     d["data"] = apply_visitor(data_visitor(shapes, strides), b);
     return d;
   }
diff --git a/test/python_suite_test.py b/test/python_suite_test.py
index cde0b048..3a97b074 100644
--- a/test/python_suite_test.py
+++ b/test/python_suite_test.py
@@ -645,16 +645,18 @@ class test_histogram(unittest.TestCase):
                     for m in range(i+j+k):
                         a.fill(i, j, k)
                     r[i,j,k] = i+j+k
-        c = numpy.array(a) # a copy
-        v = numpy.asarray(a) # a view
 
-        c2 = numpy.zeros((2, 3, 4), dtype=numpy.int8)
+        d = numpy.zeros((2, 3, 4), dtype=numpy.int8)
         for i in range(len(a.axis(0))):
             for j in range(len(a.axis(1))):
                 for k in range(len(a.axis(2))):
-                    c2[i,j,k] = a.value(i,j,k)
+                    d[i,j,k] = a.value(i,j,k)
+
+        self.assertTrue(numpy.all(d == r))
+
+        c = numpy.array(a) # a copy
+        v = numpy.asarray(a) # a view
 
-        self.assertTrue(numpy.all(c == c2))
         self.assertTrue(numpy.all(c == r))
         self.assertTrue(numpy.all(v == r))