diff --git a/matrix.cpp b/matrix.cpp
index 00ccbed8..0ea559e1 100644
--- a/matrix.cpp
+++ b/matrix.cpp
@@ -349,3 +349,26 @@ cruft::to_euler (const matrix<Rows,Cols,T> &m)
 template cruft::vector<3,float> cruft::to_euler (const matrix<3,3,float>&);
 template cruft::vector<3,float> cruft::to_euler (const matrix<4,4,float>&);
 
+
+///////////////////////////////////////////////////////////////////////////////
+#include "iterator/infix.hpp"
+#include "coord/iostream.hpp"
+
+#include <ostream>
+
+
+template <std::size_t Rows, std::size_t Cols, typename T>
+std::ostream&
+cruft::operator<< (std::ostream &os, matrix<Rows,Cols,T> const &m)
+{
+    os << '[';
+    std::copy (
+        std::cbegin (m),
+        std::cend   (m),
+        iterator::infix_iterator<decltype(m[0])> (os, ", ")
+    );
+    return os << ']';
+}
+
+
+template std::ostream& cruft::operator<< (std::ostream&, matrix<4,4,f32> const&);
\ No newline at end of file
diff --git a/matrix.hpp b/matrix.hpp
index d6bf4502..3bee6ce0 100644
--- a/matrix.hpp
+++ b/matrix.hpp
@@ -544,22 +544,11 @@ namespace cruft {
 }
 
 
-#include "iterator/infix.hpp"
-#include "coord/iostream.hpp"
-#include <ostream>
+#include <iosfwd>
 
 namespace cruft {
     ///////////////////////////////////////////////////////////////////////////
     template <std::size_t Rows, std::size_t Cols, typename T>
     std::ostream&
-    operator<< (std::ostream &os, const matrix<Rows,Cols,T> &m)
-    {
-        os << '[';
-        std::copy (
-            std::cbegin (m),
-            std::cend   (m),
-            iterator::infix_iterator<decltype(m[0])> (os, ", ")
-        );
-        return os << ']';
-    }
-};
+    operator<< (std::ostream &os, matrix<Rows,Cols,T> const&);
+}