diff --git a/core/internals.lisp b/core/internals.lisp
index 84eb2b41..eb4843d6 100644
--- a/core/internals.lisp
+++ b/core/internals.lisp
@@ -19,9 +19,13 @@
   (let ((type (or (varjo.internals::try-type-spec->type array-type nil)
                   (error 'bad-type-for-buffer-stream-data :type array-type))))
     (if (and (varjo:core-typep type) (not (varjo:v-typep type 'v-sampler)))
-        (let ((slot-layout (cepl.types::expand-slot-to-layout
-                            nil type normalized))
-              (stride 0))
+        (let* ((slot-layout (cepl.types::expand-slot-to-layout
+                             nil type normalized))
+               (stride (reduce (lambda (accum attr)
+                                 (incf accum (* (first attr)
+                                                (gl-type-size (second attr)))))
+                               slot-layout
+                               :initial-value 0)))
           (loop :for attr :in slot-layout
              :for i :from 0
              :with offset = 0
diff --git a/core/types/structs.lisp b/core/types/structs.lisp
index 46bbda1f..a969324c 100644
--- a/core/types/structs.lisp
+++ b/core/types/structs.lisp
@@ -260,7 +260,7 @@
 
 (defun+ make-varjo-struct-def (name slots)
   (let ((hidden-name (symb-package (symbol-package name)
-                                   'v_ name )))
+                                   'v_ name)))
     `(v-defstruct
          (,name :shadowing ,hidden-name)
          ()
@@ -465,11 +465,16 @@
 
 (defun+ make-struct-attrib-assigner (type-name slots)
   (when (every #'buffer-stream-compatible-typep slots)
-    (let* ((stride (if (> (length slots) 1)
+    (let* ((def-sets (mapcat #'expand-slot-to-layout slots))
+           (stride (if (> (length slots) 1)
                        `(cepl.internals:gl-type-size ',type-name)
-                       0))
+                       (reduce (lambda (accum attr)
+                                 (incf accum (* (first attr)
+                                                (cepl.internals:gl-type-size
+                                                 (second attr)))))
+                               def-sets
+                               :initial-value 0)))
            (stride-sym (gensym "stride"))
-           (def-sets (mapcat #'expand-slot-to-layout slots))
            (definitions
             (loop :for (len cffi-type normalized gl-type)
                :in def-sets