diff --git a/doc/source/reference/c-api.config.rst b/doc/source/reference/c-api.config.rst
index 0989c53d7ee7..9978434fcd81 100644
--- a/doc/source/reference/c-api.config.rst
+++ b/doc/source/reference/c-api.config.rst
@@ -34,10 +34,10 @@ information is available to the pre-processor.
 
     sizeof(long)
 
-.. cvar:: NPY_SIZEOF_LONG_LONG
+.. cvar:: NPY_SIZEOF_LONGLONG
 
     sizeof(longlong) where longlong is defined appropriately on the
-    platform (A macro defines **NPY_SIZEOF_LONGLONG** as well.)
+    platform.
 
 .. cvar:: NPY_SIZEOF_PY_LONG_LONG
 
diff --git a/numpy/core/src/multiarray/buffer.c b/numpy/core/src/multiarray/buffer.c
index 530edbb1ac23..35156e72a65d 100644
--- a/numpy/core/src/multiarray/buffer.c
+++ b/numpy/core/src/multiarray/buffer.c
@@ -299,11 +299,11 @@ _buffer_format_string(PyArray_Descr *descr, _tmp_string_t *str,
         int is_standard_size = 1;
         int is_native_only_type = (descr->type_num == NPY_LONGDOUBLE ||
                                    descr->type_num == NPY_CLONGDOUBLE);
-#if NPY_SIZEOF_LONG_LONG != 8
-        is_native_only_type = is_native_only_type || (
-            descr->type_num == NPY_LONGLONG ||
-            descr->type_num == NPY_ULONGLONG);
-#endif
+        if (sizeof(npy_longlong) != 8) {
+            is_native_only_type = is_native_only_type || (
+                descr->type_num == NPY_LONGLONG ||
+                descr->type_num == NPY_ULONGLONG);
+        }
 
         *offset += descr->elsize;
 
@@ -339,6 +339,7 @@ _buffer_format_string(PyArray_Descr *descr, _tmp_string_t *str,
                              "cannot expose native-only dtype '%c' in "
                              "non-native byte order '%c' via buffer interface",
                              descr->type, descr->byteorder);
+                return -1;
             }
         }
 
diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
index 6697b8131ed9..5fb53fbb1505 100644
--- a/numpy/core/tests/test_multiarray.py
+++ b/numpy/core/tests/test_multiarray.py
@@ -2650,17 +2650,21 @@ def test_roundtrip(self):
             x = np.array([1,2,3], dtype='<i4')
             self._check_roundtrip(x)
 
+            # check long long can be represented as non-native
+            x = np.array([1, 2, 3], dtype='>q')
+            self._check_roundtrip(x)
+
             # Native-only data types can be passed through the buffer interface
             # only in native byte order
             if sys.byteorder == 'little':
-                x = np.array([1,2,3], dtype='>q')
+                x = np.array([1,2,3], dtype='>g')
                 assert_raises(ValueError, self._check_roundtrip, x)
-                x = np.array([1,2,3], dtype='<q')
+                x = np.array([1,2,3], dtype='<g')
                 self._check_roundtrip(x)
             else:
-                x = np.array([1,2,3], dtype='>q')
+                x = np.array([1,2,3], dtype='>g')
                 self._check_roundtrip(x)
-                x = np.array([1,2,3], dtype='<q')
+                x = np.array([1,2,3], dtype='<g')
                 assert_raises(ValueError, self._check_roundtrip, x)
 
         def test_roundtrip_half(self):
@@ -2746,9 +2750,9 @@ def test_export_record(self):
 
             sz = sum([dtype(b).itemsize for a, b in dt])
             if dtype('l').itemsize == 4:
-                assert_equal(y.format, 'T{b:a:=h:b:i:c:l:d:^q:dx:B:e:@H:f:=I:g:L:h:^Q:hx:=f:i:d:j:^g:k:=Zf:ix:Zd:jx:^Zg:kx:4s:l:=4w:m:3x:n:?:o:@e:p:}')
+                assert_equal(y.format, 'T{b:a:=h:b:i:c:l:d:q:dx:B:e:@H:f:=I:g:L:h:Q:hx:f:i:d:j:^g:k:=Zf:ix:Zd:jx:^Zg:kx:4s:l:=4w:m:3x:n:?:o:@e:p:}')
             else:
-                assert_equal(y.format, 'T{b:a:=h:b:i:c:q:d:^q:dx:B:e:@H:f:=I:g:Q:h:^Q:hx:=f:i:d:j:^g:k:=Zf:ix:Zd:jx:^Zg:kx:4s:l:=4w:m:3x:n:?:o:@e:p:}')
+                assert_equal(y.format, 'T{b:a:=h:b:i:c:q:d:q:dx:B:e:@H:f:=I:g:Q:h:Q:hx:f:i:d:j:^g:k:=Zf:ix:Zd:jx:^Zg:kx:4s:l:=4w:m:3x:n:?:o:@e:p:}')
             assert_equal(y.strides, (sz,))
             assert_equal(y.itemsize, sz)