2 files changed, 28 insertions, 5 deletions
diff --git a/tests/process/buildfile b/tests/process/buildfile
index ddb4688..2ecc915 100644
--- a/tests/process/buildfile
+++ b/tests/process/buildfile
@@ -4,4 +4,10 @@
 
 import libs = libbutl%lib{butl}
 
+if ($cxx.features.modules && ($force_std_modules == true || $cxx.id != 'msvc'))
+{
+  import libs += libstd-modules%liba{std-modules}
+  cxx.poptions += -D__cpp_lib_modules
+}
+
 exe{driver}: {hxx cxx}{*} $libs test{testscript}
diff --git a/tests/process/driver.cxx b/tests/process/driver.cxx
index 0338af2..01f2c30 100644
--- a/tests/process/driver.cxx
+++ b/tests/process/driver.cxx
@@ -4,17 +4,34 @@
 
 #include <stdlib.h> // getenv(), setenv(), _putenv()
 
+#include <cassert>
+
+#ifndef __cpp_lib_modules
 #include <ios>
 #include <string>
 #include <vector>
-#include <cassert>
-#include <iostream>
 #include <iterator>  // istreambuf_iterator, ostream_iterator
 #include <algorithm> // copy()
+#include <iostream>
+#endif
+
+// Other includes.
 
-#include <libbutl/path.hxx>
-#include <libbutl/process.hxx>
-#include <libbutl/fdstream.hxx>
+#ifdef __cpp_modules
+#ifdef __cpp_lib_modules
+import std.core;
+import std.io;
+#endif
+import butl.path;
+import butl.process;
+import butl.optional;
+import butl.fdstream;
+#else
+#include <libbutl/path.mxx>
+#include <libbutl/process.mxx>
+#include <libbutl/optional.mxx>
+#include <libbutl/fdstream.mxx>
+#endif
 
 using namespace std;
 using namespace butl;