diff --git a/g13d/CMakeLists.txt b/g13d/CMakeLists.txt
index d67475f..0b98cf5 100644
--- a/g13d/CMakeLists.txt
+++ b/g13d/CMakeLists.txt
@@ -19,6 +19,7 @@ add_executable(g13d
   main.cc
   stick.cc
   manager.cc
+  repr.cc
 )
 
 target_compile_definitions(g13d PRIVATE BOOST_LOG_DYN_LINK=1)
diff --git a/g13d/repr.cc b/g13d/repr.cc
new file mode 100644
index 0000000..7ce0c1b
--- /dev/null
+++ b/g13d/repr.cc
@@ -0,0 +1,55 @@
+#include <ostream>
+
+#include "repr.h"
+
+namespace G13 {
+
+void string_repr_out::write_on(std::ostream &o) const {
+  const char *cp = s.c_str();
+  const char *end = cp + s.size();
+
+  o << "\"";
+
+  while (cp < end) {
+    switch (*cp) {
+      case '\n':
+        o << "\\n";
+        break;
+
+      case '\r':
+        o << "\\r";
+        break;
+
+      case '\0':
+        o << "\\0";
+        break;
+
+      case '\t':
+        o << "\\t";
+        break;
+
+      case '\\':
+      case '\'':
+      case '\"':
+        o << "\\" << *cp;
+        break;
+
+      default: {
+        char c = *cp;
+        if (c < 32) {
+          char hi = '0' + (c & 0x0f);
+          char lo = '0' + ((c >> 4) & 0x0f);
+          o << "\\x" << hi << lo;
+        } else {
+          o << c;
+        }
+      }
+    }
+
+    cp++;
+  }
+
+  o << "\"";
+};
+
+} // namespace G13
diff --git a/g13d/repr.h b/g13d/repr.h
index dc9c383..b184ac9 100644
--- a/g13d/repr.h
+++ b/g13d/repr.h
@@ -6,54 +6,6 @@
 
 namespace G13 {
 
-void string_repr_out::write_on(std::ostream &o) const {
-  const char *cp = s.c_str();
-  const char *end = cp + s.size();
-
-  o << "\"";
-
-  while (cp < end) {
-    switch (*cp) {
-      case '\n':
-        o << "\\n";
-        break;
-
-      case '\r':
-        o << "\\r";
-        break;
-
-      case '\0':
-        o << "\\0";
-        break;
-
-      case '\t':
-        o << "\\t";
-        break;
-
-      case '\\':
-      case '\'':
-      case '\"':
-        o << "\\" << *cp;
-        break;
-
-      default: {
-        char c = *cp;
-        if (c < 32) {
-          char hi = '0' + (c & 0x0f);
-          char lo = '0' + ((c >> 4) & 0x0f);
-          o << "\\x" << hi << lo;
-        } else {
-          o << c;
-        }
-      }
-    }
-
-    cp++;
-  }
-
-  o << "\"";
-};
-
 struct string_repr_out {
   string_repr_out(const std::string &str) : s(str) {}
   void write_on(std::ostream &) const;