diff --git a/debug/assert.hpp b/debug/assert.hpp
index 89db782c..f867c7d7 100644
--- a/debug/assert.hpp
+++ b/debug/assert.hpp
@@ -18,6 +18,9 @@
 
 #include <utility>
 
+#ifndef NDEBUG
+#include <iostream>
+#endif
 
 ///////////////////////////////////////////////////////////////////////////////
 #ifdef COMPILER_GCC
diff --git a/debug/common.hpp b/debug/common.hpp
index bd81ea99..af0b59ff 100644
--- a/debug/common.hpp
+++ b/debug/common.hpp
@@ -29,7 +29,6 @@
 /// refer to variables which do not always exist, and current compiler
 /// implementations are a little picky here.
 #ifndef NDEBUG
-    #include <iostream>
     #define DEBUG_ONLY(X) do { X; } while (0)
 #else
     #define DEBUG_ONLY(X) do {  ; } while (0)