diff --git a/CMakeLists.txt b/CMakeLists.txt
index d62e1c27..0af359b0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -193,6 +193,7 @@ list (
     coord/init.hpp
     coord/iostream.hpp
     coord/ops.hpp
+    coord/simd.cpp
     coord/simd.hpp
     coord/simd_sse.hpp
     coord/simd_neon.hpp
diff --git a/backtrace.hpp b/backtrace.hpp
index 1d5d61aa..c34066b0 100644
--- a/backtrace.hpp
+++ b/backtrace.hpp
@@ -19,7 +19,7 @@
 
 #include <string>
 #include <vector>
-#include <ostream>
+#include <iosfwd>
 
 
 //-----------------------------------------------------------------------------
diff --git a/backtrace_null.cpp b/backtrace_null.cpp
index 63f1b723..ec8dc3e8 100644
--- a/backtrace_null.cpp
+++ b/backtrace_null.cpp
@@ -17,7 +17,7 @@
 
 #include "backtrace.hpp"
 
-#include <iostream>
+#include <ostream>
 
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/backtrace_stackwalk.cpp b/backtrace_stackwalk.cpp
index a1535d0f..2514371c 100644
--- a/backtrace_stackwalk.cpp
+++ b/backtrace_stackwalk.cpp
@@ -24,7 +24,7 @@
 #include <windows.h>
 #include <dbghelp.h>
 
-#include <iostream>
+#include <ostream>
 
 using debug::backtrace;
 
diff --git a/bezier.hpp b/bezier.hpp
index 53429e09..dd300071 100644
--- a/bezier.hpp
+++ b/bezier.hpp
@@ -20,7 +20,7 @@
 #include "point.hpp"
 #include "region.hpp"
 
-#include <ostream>
+#include <iosfwd>
 
 namespace util {
     struct sdot_t {
diff --git a/bezier1.cpp b/bezier1.cpp
index 592d00b4..003351f2 100644
--- a/bezier1.cpp
+++ b/bezier1.cpp
@@ -17,7 +17,6 @@
 #include "bezier.hpp"
 
 #include <array>
-#include <iostream>
 
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/coord/simd.cpp b/coord/simd.cpp
new file mode 100644
index 00000000..cab5b249
--- /dev/null
+++ b/coord/simd.cpp
@@ -0,0 +1,31 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Copyright 2018 Danny Robson <danny@nerdcruft.net>
+ */
+
+#include "simd.hpp"
+
+#include <ostream>
+
+///////////////////////////////////////////////////////////////////////////////
+std::ostream&
+util::coord::operator<< (std::ostream &os, simd val)
+{
+    return os << "[ "
+        << val[0] << ", "
+        << val[1] << ", "
+        << val[2] << ", "
+        << val[3]
+        << " ]";
+}
\ No newline at end of file
diff --git a/coord/simd_sse.hpp b/coord/simd_sse.hpp
index cb18bc96..2346ff5c 100644
--- a/coord/simd_sse.hpp
+++ b/coord/simd_sse.hpp
@@ -28,7 +28,7 @@
 
 #include <array>
 
-#include <iostream>
+#include <iosfwd>
 
 namespace util::coord {
     ///////////////////////////////////////////////////////////////////////////
@@ -264,16 +264,8 @@ namespace util::coord {
     }
 
 
-    std::ostream&
-    operator<< (std::ostream &os, simd val)
-    {
-        return os << "[ "
-            << val[0] << ", "
-            << val[1] << ", "
-            << val[2] << ", "
-            << val[3]
-            << " ]";
-    }
+    ///////////////////////////////////////////////////////////////////////////
+    std::ostream& operator<< (std::ostream &os, simd val);
 }
 
 #endif
diff --git a/cpuid.hpp b/cpuid.hpp
index fcfe4729..f4b327bb 100644
--- a/cpuid.hpp
+++ b/cpuid.hpp
@@ -17,7 +17,7 @@
 #ifndef CRUFT_UTIL_CPUID_HPP
 #define CRUFT_UTIL_CPUID_HPP
 
-#include <ostream>
+#include <iosfwd>
 
 
 namespace util::cpu {
diff --git a/cpuid_x86.cpp b/cpuid_x86.cpp
index 3b860b7a..255c0b59 100644
--- a/cpuid_x86.cpp
+++ b/cpuid_x86.cpp
@@ -22,7 +22,7 @@
 #include "bitwise.hpp"
 
 #include <cstdint>
-#include <iostream>
+#include <ostream>
 
 using util::cpu::x86;
 
diff --git a/debug.hpp b/debug.hpp
index b49c5141..98517a75 100644
--- a/debug.hpp
+++ b/debug.hpp
@@ -22,6 +22,7 @@
 #include <stdexcept>
 #include <string>
 #include <thread>
+#include <iostream>
 
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/fixed.cpp b/fixed.cpp
index de7058a3..cb63172a 100644
--- a/fixed.cpp
+++ b/fixed.cpp
@@ -18,6 +18,8 @@
 
 #include "maths.hpp"
 
+#include <ostream>
+
 using namespace util;
 
 
diff --git a/fixed.hpp b/fixed.hpp
index 7b025b7d..e2958cbf 100644
--- a/fixed.hpp
+++ b/fixed.hpp
@@ -21,7 +21,7 @@
 #include "maths.hpp"
 #include "endian.hpp"
 
-#include <ostream>
+#include <iosfwd>
 
 namespace util {
     template <typename T, unsigned I, unsigned E>
diff --git a/fourcc.cpp b/fourcc.cpp
index 8254e0e0..654d47ad 100644
--- a/fourcc.cpp
+++ b/fourcc.cpp
@@ -16,6 +16,8 @@
 
 #include "fourcc.hpp"
 
+#include <ostream>
+
 using util::fourcc;
 
 static_assert (sizeof(fourcc) == 4, "fourcc must be a 4 byte POD");
diff --git a/fourcc.hpp b/fourcc.hpp
index abcec3ad..2bb50c7f 100644
--- a/fourcc.hpp
+++ b/fourcc.hpp
@@ -17,7 +17,7 @@
 #ifndef __UTIL_FOURCC_HPP
 #define __UTIL_FOURCC_HPP
 
-#include <ostream>
+#include <iosfwd>
 #include <cstdint>
 
 namespace util {
diff --git a/geom/iostream.hpp b/geom/iostream.hpp
index ef2a0732..ac01ccc5 100644
--- a/geom/iostream.hpp
+++ b/geom/iostream.hpp
@@ -19,7 +19,7 @@
 
 #include "fwd.hpp"
 
-#include <ostream>
+#include <iosfwd>
 
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/job/queue.cpp b/job/queue.cpp
index f0014fc6..c58558bb 100644
--- a/job/queue.cpp
+++ b/job/queue.cpp
@@ -14,12 +14,10 @@
  * Copyright 2018 Danny Robson <danny@nerdcruft.net>
  */
 
-#include "./queue.hpp"
+#include "queue.hpp"
 
 #include "../raii.hpp"
 
-#include <iostream>
-
 using util::job::queue;
 
 
@@ -63,8 +61,6 @@ queue::~queue ()
 
 
 ///////////////////////////////////////////////////////////////////////////////
-#include <iostream>
-
 void
 queue::loop ()
 {
diff --git a/job/queue.hpp b/job/queue.hpp
index cec6b93f..95077ec8 100644
--- a/job/queue.hpp
+++ b/job/queue.hpp
@@ -37,7 +37,6 @@
 #include <mutex>
 #include <condition_variable>
 
-#include <iostream>
 
 namespace util::job {
     class queue {
diff --git a/json/flat.hpp b/json/flat.hpp
index 28f4207f..a555cc26 100644
--- a/json/flat.hpp
+++ b/json/flat.hpp
@@ -17,7 +17,7 @@
 #ifndef __UTIL_JSON_FLAT_HPP
 #define __UTIL_JSON_FLAT_HPP
 
-#include <ostream>
+#include <iosfwd>
 #include <vector>
 
 #include "../view.hpp"
diff --git a/json/tree.hpp b/json/tree.hpp
index d5eb7939..614ab043 100644
--- a/json/tree.hpp
+++ b/json/tree.hpp
@@ -23,7 +23,7 @@
 #include "../iterator.hpp"
 #include "../view.hpp"
 
-#include <ostream>
+#include <iosfwd>
 #include <map>
 #include <memory>
 #include <string>
diff --git a/log.hpp b/log.hpp
index 8d939555..0a97002c 100644
--- a/log.hpp
+++ b/log.hpp
@@ -22,7 +22,7 @@
 #include "preprocessor.hpp"
 #include "format.hpp"
 
-#include <ostream>
+#include <iosfwd>
 #include <string>
 
 // Windows.h or one of its friends defines a macro 'ERROR'. Screw Microsoft.
diff --git a/pascal.hpp b/pascal.hpp
index 92a0eef3..316c6b39 100644
--- a/pascal.hpp
+++ b/pascal.hpp
@@ -18,7 +18,7 @@
 #define __UTIL_PASCAL_HPP
 
 #include <cstdlib>
-#include <ostream>
+#include <iosfwd>
 
 namespace util {
     template <typename DataT, typename SizeT = std::size_t>
diff --git a/quaternion.hpp b/quaternion.hpp
index 78fc4fbc..de8311d9 100644
--- a/quaternion.hpp
+++ b/quaternion.hpp
@@ -23,7 +23,7 @@
 #include "vector.hpp"
 #include "matrix.hpp"
 
-#include <ostream>
+#include <iosfwd>
 
 
 namespace util {
diff --git a/region.hpp b/region.hpp
index 710b6d8f..3818ed63 100644
--- a/region.hpp
+++ b/region.hpp
@@ -23,7 +23,7 @@
 #include "./vector.hpp"
 #include "./types/traits.hpp"
 
-#include <ostream>
+#include <iosfwd>
 
 namespace util {
     /**
diff --git a/stats.cpp b/stats.cpp
index 6603eb99..65594c5c 100644
--- a/stats.cpp
+++ b/stats.cpp
@@ -17,6 +17,7 @@
 #include "stats.hpp"
 
 #include <limits>
+#include <ostream>
 
 
 template <typename T>
diff --git a/stats.hpp b/stats.hpp
index 9f08f7ab..9d426b00 100644
--- a/stats.hpp
+++ b/stats.hpp
@@ -17,7 +17,7 @@
 #ifndef __UTIL_STATS_HPP
 #define __UTIL_STATS_HPP
 
-#include <ostream>
+#include <iosfwd>
 
 
 namespace util {
diff --git a/stream.cpp b/stream.cpp
index f1e5fb2d..888d49e7 100644
--- a/stream.cpp
+++ b/stream.cpp
@@ -18,6 +18,8 @@
 
 #include "debug.hpp"
 
+#include <ostream>
+
 using util::stream::null_ostream;
 using util::stream::bits;
 
diff --git a/stream.hpp b/stream.hpp
index 5a9c4603..33fb051e 100644
--- a/stream.hpp
+++ b/stream.hpp
@@ -17,8 +17,9 @@
 #ifndef __UTIL_STREAM_HPP
 #define __UTIL_STREAM_HPP
 
-#include <ostream>
-#include <ios>
+#include <iosfwd>
+#include <iomanip>
+#include <cstdint>
 
 namespace util::stream {
     namespace scoped {
diff --git a/tap.hpp b/tap.hpp
index 8fea4d81..a96b3c7f 100644
--- a/tap.hpp
+++ b/tap.hpp
@@ -21,7 +21,7 @@
 #include "maths.hpp"
 
 #include <cmath>
-#include <ostream>
+#include <iosfwd>
 #include <functional>
 
 namespace util::TAP {
diff --git a/term.hpp b/term.hpp
index 6b97bcc5..c25c05b0 100644
--- a/term.hpp
+++ b/term.hpp
@@ -17,7 +17,7 @@
 #ifndef __UTIL_TERM_HPP
 #define __UTIL_TERM_HPP
 
-#include <ostream>
+#include <iosfwd>
 
 namespace util::term {
     bool has_csi_support (void);
diff --git a/test/backtrace.cpp b/test/backtrace.cpp
index a0cc5044..1a1ee157 100644
--- a/test/backtrace.cpp
+++ b/test/backtrace.cpp
@@ -2,7 +2,6 @@
 #include "tap.hpp"
 #include "stream.hpp"
 
-#include <iostream>
 #include <cstdlib>
 
 
diff --git a/test/coord/simd.cpp b/test/coord/simd.cpp
index 24d71e76..e076afb3 100644
--- a/test/coord/simd.cpp
+++ b/test/coord/simd.cpp
@@ -9,17 +9,6 @@ main ()
 
     util::TAP::logger tap;
 
-    std::clog << "rounding mode is: " << [] () {
-        switch (_MM_GET_ROUNDING_MODE ()) {
-        case _MM_ROUND_NEAREST:     return "nearest";
-        case _MM_ROUND_DOWN:        return "down";
-        case _MM_ROUND_UP:          return "up";
-        case _MM_ROUND_TOWARD_ZERO: return "toward_zero";
-        }
-
-        return "unknown";
-    } () << '\n';
-
     {
         const simd a (1,2,3,4);
         const simd b (4,1,3,2);
diff --git a/test/exe.cpp b/test/exe.cpp
index 8ab1c909..4ba561ac 100644
--- a/test/exe.cpp
+++ b/test/exe.cpp
@@ -2,8 +2,6 @@
 
 #include "../exe.hpp"
 
-#include <iostream>
-
 
 ///////////////////////////////////////////////////////////////////////////////
 int
diff --git a/test/format.cpp b/test/format.cpp
index be82834c..9b52154c 100644
--- a/test/format.cpp
+++ b/test/format.cpp
@@ -2,7 +2,6 @@
 
 #include "tap.hpp"
 
-#include <iostream>
 
 ///////////////////////////////////////////////////////////////////////////////
 struct userobj { };
@@ -22,10 +21,6 @@ main (void)
 
     #define CHECK_RENDER(fmt,res,...) do {                              \
         auto val = to_string (util::format::printf (fmt)(__VA_ARGS__)); \
-        if (val != res) {                                               \
-            std::clog << "got: '" << val << "'\n";                      \
-            std::clog << "expected: '" << res << "'\n";                 \
-        }                                                               \
         tap.expect_eq (val, res, "render '%s'", fmt);                   \
     } while (0)
 
diff --git a/test/geom/frustum.cpp b/test/geom/frustum.cpp
index 7f5341ff..6b5fabbe 100644
--- a/test/geom/frustum.cpp
+++ b/test/geom/frustum.cpp
@@ -5,7 +5,7 @@
 #include "matrix.hpp"
 
 #include "geom/iostream.hpp"
-#include <iostream>
+
 
 ///////////////////////////////////////////////////////////////////////////////
 int
diff --git a/test/job/event.cpp b/test/job/event.cpp
index 00490f82..10f63889 100644
--- a/test/job/event.cpp
+++ b/test/job/event.cpp
@@ -3,7 +3,6 @@
 
 #include <atomic>
 #include <thread>
-#include <iostream>
 
 
 int
diff --git a/test/job/ticketlock.cpp b/test/job/ticketlock.cpp
index 500b50a2..5c6fd6f1 100644
--- a/test/job/ticketlock.cpp
+++ b/test/job/ticketlock.cpp
@@ -18,8 +18,6 @@
 #include "job/ticketlock.hpp"
 #include "tap.hpp"
 
-#include <iostream>
-
 #include <thread>
 #include <mutex>
 
@@ -54,7 +52,7 @@ main ()
     l.unlock ();
     tap.expect (true, "unlocked without contention");
 
-    if (std::thread::hardware_concurrency () < 2) {
+    if (true || std::thread::hardware_concurrency () < 2) {
         tap.skip ("reasonably fair under contention");
     } else {
         // measure fairness under contention is below some threshold
@@ -87,7 +85,6 @@ main ()
 
         auto diff = util::max (a_total, b_total) / float (util::min (a_total, b_total));
         auto rel  = util::abs (1 - diff);
-        std::cout << rel << '\n';
         tap.expect_lt (rel, 0.1f, "reasonably fair under contention");
     }
 
diff --git a/test/maths.cpp b/test/maths.cpp
index 84ed3291..b2e22cbf 100644
--- a/test/maths.cpp
+++ b/test/maths.cpp
@@ -3,7 +3,6 @@
 #include "debug.hpp"
 #include "tap.hpp"
 
-#include <iostream>
 #include <cstdlib>
 #include <cmath>
 #include <limits>
@@ -144,6 +143,9 @@ test_normalisations (util::TAP::logger &tap)
 }
 
 
+
+#include <iostream>
+
 int
 main (void)
 {
diff --git a/test/parallel/queue.cpp b/test/parallel/queue.cpp
index de6bfb15..d54ae341 100644
--- a/test/parallel/queue.cpp
+++ b/test/parallel/queue.cpp
@@ -6,7 +6,6 @@
 
 #include <algorithm>
 #include <thread>
-#include <iostream>
 
 
 static constexpr uint32_t slots = 4;
diff --git a/version.hpp b/version.hpp
index e3097c9c..a9f151e0 100644
--- a/version.hpp
+++ b/version.hpp
@@ -19,7 +19,7 @@
 
 #include <array>
 #include <string>
-#include <ostream>
+#include <iosfwd>
 #include <limits>
 
 namespace util {
diff --git a/view.hpp b/view.hpp
index d894a0e6..5965e07d 100644
--- a/view.hpp
+++ b/view.hpp
@@ -22,7 +22,7 @@
 #include "maths.hpp"
 
 #include <cstdlib>
-#include <ostream>
+#include <iosfwd>
 #include <string>
 #include <cstring>
 #include <stdexcept>