diff --git a/src/lib/iter-stack.hpp b/src/lib/iter-stack.hpp
index 681233d45..16b9511f5 100644
--- a/src/lib/iter-stack.hpp
+++ b/src/lib/iter-stack.hpp
@@ -67,8 +67,9 @@
 
 namespace lib {
   
+  using util::unConst;
+  
   namespace iter {
-    using util::unConst;
     
     /**
      * Wrapper to mark a std::deque instance for use
@@ -153,6 +154,21 @@ namespace lib {
           this->stateCore().pop_back();
           return topElement;
         }
+      
+      
+      /* == diagnostics == */
+      
+      size_t
+      size()  const
+        {
+          return unConst(this)->stateCore().size();
+        }
+      
+      bool
+      empty() const
+        {
+          return 0 == size();
+        }
     };
   
   
@@ -208,6 +224,21 @@ namespace lib {
         }
       
       
+      /* == diagnostics == */
+      
+      size_t
+      size()  const
+        {
+          return unConst(this)->stateCore().size();
+        }
+      
+      bool
+      empty() const
+        {
+          return 0 == size();
+        }
+      
+      
       /** 
        * Adapter for use as opaque sequence.
        * This builder exposes generic operations
diff --git a/src/proc/control/command-queue.hpp b/src/proc/control/command-queue.hpp
index cc82b1c69..a5b54ec3a 100644
--- a/src/proc/control/command-queue.hpp
+++ b/src/proc/control/command-queue.hpp
@@ -87,21 +87,6 @@ namespace control {
         {
           this->stateCore().clear();
         }
-      
-      
-      /* == diagnostics == */
-      
-      size_t
-      size() const
-        {
-          return unConst(this)->stateCore().size();
-        }
-      
-      bool
-      empty()  const
-        {
-          return 0 == size();
-        }
     };