diff --git a/src/octet/spec.cljc b/src/octet/spec.cljc
index f315939..0fe2802 100644
--- a/src/octet/spec.cljc
+++ b/src/octet/spec.cljc
@@ -73,9 +73,9 @@
   (size* [_ data]
     (reduce (fn [acc [field data]]
               (let [type (field dict)]
-                (if (satisfies? ISpecSize type)
-                  (+ acc (size type))
-                  (+ acc (size* type data)))))
+                (if (satisfies? ISpecDynamicSize type)
+                  (+ acc (size* type data))
+                  (+ acc (size type)))))
             0
             (into [] data)))
 
diff --git a/test/octet/tests/core.cljc b/test/octet/tests/core.cljc
index 556fd75..c561a71 100644
--- a/test/octet/tests/core.cljc
+++ b/test/octet/tests/core.cljc
@@ -466,6 +466,16 @@
       (t/is (= readed 24))
       (t/is (= data [1 2 3 4 5])))))
 
+(t/deftest spec-associative-nested-dynamic
+  (let [spec (buf/spec :outer (buf/spec :inner (buf/vector* buf/int32)))
+        buffer (buf/into (buf/spec :outer (buf/spec :inner (buf/vector* buf/int32))) {:outer {:inner [1]}})
+        written (impl/get-capacity buffer)]
+    (t/is (= written 8))
+
+    (let [[readed data] (buf/read* buffer spec)]
+      (t/is (= readed 8)
+        (t/is (= data {:outer {:inner [1]}}))))))
+
 #?(:cljs
    (do
      (enable-console-print!)