diff --git a/octa/array.hh b/octa/array.hh
index a8869d9..4c58502 100644
--- a/octa/array.hh
+++ b/octa/array.hh
@@ -16,7 +16,7 @@ namespace octa {
 
 template<typename T, Size N>
 struct Array {
-    using Size = Size;
+    using Size = octa::Size;
     using Difference = Ptrdiff;
     using Value = T;
     using Reference = T &;
diff --git a/octa/map.hh b/octa/map.hh
index 5efe30f..3da9fdc 100644
--- a/octa/map.hh
+++ b/octa/map.hh
@@ -51,7 +51,7 @@ namespace detail {
     public:
         using Key = K;
         using Mapped = T;
-        using Size = Size;
+        using Size = octa::Size;
         using Difference = Ptrdiff;
         using Hasher = H;
         using KeyEqual = C;
diff --git a/octa/memory.hh b/octa/memory.hh
index 9f07d8e..79715de 100644
--- a/octa/memory.hh
+++ b/octa/memory.hh
@@ -483,7 +483,7 @@ private:
 
 namespace detail {
     template<typename T> struct BoxIf {
-        using Box = Box<T>;
+        using BoxType = Box<T>;
     };
 
     template<typename T> struct BoxIf<T[]> {
@@ -496,7 +496,7 @@ namespace detail {
 }
 
 template<typename T, typename ...A>
-typename detail::BoxIf<T>::Box make_box(A &&...args) {
+typename detail::BoxIf<T>::BoxType make_box(A &&...args) {
     return Box<T>(new T(forward<A>(args)...));
 }
 
@@ -529,7 +529,7 @@ template<> struct Allocator<const void> {
 };
 
 template<typename T> struct Allocator {
-    using Size = Size;
+    using Size = octa::Size;
     using Difference = Ptrdiff;
     using Value = T;
     using Reference = T &;
@@ -566,7 +566,7 @@ template<typename T> struct Allocator {
 };
 
 template<typename T> struct Allocator<const T> {
-    using Size = Size;
+    using Size = octa::Size;
     using Difference = Ptrdiff;
     using Value = const T;
     using Reference = const T &;
diff --git a/octa/set.hh b/octa/set.hh
index 92ceb2f..32e9639 100644
--- a/octa/set.hh
+++ b/octa/set.hh
@@ -40,7 +40,7 @@ namespace detail {
 
     public:
         using Key = T;
-        using Size = Size;
+        using Size = octa::Size;
         using Difference = Ptrdiff;
         using Hasher = H;
         using KeyEqual = C;
diff --git a/octa/string.hh b/octa/string.hh
index 22dc4ca..f54dfb8 100644
--- a/octa/string.hh
+++ b/octa/string.hh
@@ -149,7 +149,7 @@ class StringBase {
     }
 
 public:
-    using Size = Size;
+    using Size = octa::Size;
     using Difference = Ptrdiff;
     using Value = T;
     using Reference = T &;
diff --git a/octa/vector.hh b/octa/vector.hh
index f69efbe..ac5dcb4 100644
--- a/octa/vector.hh
+++ b/octa/vector.hh
@@ -18,14 +18,11 @@
 
 namespace octa {
 
-namespace detail {
-} /* namespace detail */
-
 template<typename T, typename A = Allocator<T>>
 class Vector {
     using VecPair = detail::CompressedPair<AllocatorPointer<A>, A>;
 
-    Size p_len, p_cap;
+    octa::Size p_len, p_cap;
     VecPair p_buf;
 
     void insert_base(Size idx, Size n) {
@@ -77,7 +74,7 @@ class Vector {
     }
 
 public:
-    using Size = Size;
+    using Size = octa::Size;
     using Difference = Ptrdiff;
     using Value = T;
     using Reference = T &;