diff --git a/src/Kaleidoscope-HostOS.h b/src/Kaleidoscope-HostOS.h
index f3295a91..c3f9fd96 100644
--- a/src/Kaleidoscope-HostOS.h
+++ b/src/Kaleidoscope-HostOS.h
@@ -20,3 +20,4 @@
 
 #include <Kaleidoscope/HostOS-Base.h>
 #include <Kaleidoscope/HostOS-Guesser.h>
+#include <Kaleidoscope/HostOS-Focus.h>
diff --git a/src/Kaleidoscope/HostOS-Focus.cpp b/src/Kaleidoscope/HostOS-Focus.cpp
new file mode 100644
index 00000000..fe5b45b3
--- /dev/null
+++ b/src/Kaleidoscope/HostOS-Focus.cpp
@@ -0,0 +1,54 @@
+/* -*- mode: c++ -*-
+ * Kaleidoscope-HostOS -- Host OS detection and tracking for Kaleidoscope
+ * Copyright (C) 2016, 2017  Gergely Nagy
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <Kaleidoscope/HostOS-Base.h>
+#include <Kaleidoscope/HostOS-Focus.h>
+
+namespace KaleidoscopePlugins {
+  namespace HostOS {
+    bool
+    Focus (const char *command) {
+      enum {
+        GET,
+        SET,
+      } subCommand;
+
+      if (strncmp_P (command, PSTR ("hostos."), 7) != 0)
+        return false;
+      if (strcmp_P (command + 7, PSTR ("type")) == 0)
+        subCommand = GET;
+      else if (strcmp_P (command + 7, PSTR ("set")) == 0)
+        subCommand = SET;
+      else
+        return false;
+
+      switch (subCommand) {
+      case GET:
+        Serial.println (::HostOS.os ());
+        break;
+      case SET:
+        uint8_t os = Serial.parseInt ();
+        ::HostOS.os ((KaleidoscopePlugins::HostOS::Type) os);
+        break;
+      }
+
+      Serial.read ();
+      return true;
+    }
+  }
+}
diff --git a/src/Kaleidoscope/HostOS-Focus.h b/src/Kaleidoscope/HostOS-Focus.h
new file mode 100644
index 00000000..7d104b76
--- /dev/null
+++ b/src/Kaleidoscope/HostOS-Focus.h
@@ -0,0 +1,36 @@
+/* -*- mode: c++ -*-
+ * Kaleidoscope-HostOS -- Host OS detection and tracking for Kaleidoscope
+ * Copyright (C) 2016, 2017  Gergely Nagy
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <Kaleidoscope/HostOS-Base.h>
+
+namespace KaleidoscopePlugins {
+  namespace HostOS {
+    bool Focus (const char *command);
+  };
+};
+
+#define FOCUS_HOOK_HOSTOS                                       \
+  FOCUS_HOOK(KaleidoscopePlugins::HostOS::Focus,                \
+             "hostos.type\n"                                    \
+             "-----------\n"                                    \
+             "Display the OS type, as known to the plugin.\n\n" \
+             "hostos.set type\n"                                \
+             "---------------\n"                                \
+             "Set the OS type.")