diff --git a/tools/io.hpp b/tools/io.hpp
index b3b2c79..8925418 100644
--- a/tools/io.hpp
+++ b/tools/io.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "internal/sys.hpp"
+#include "io_interface.hpp"
 
 #include <cstdint>
 #include <string>
@@ -8,37 +9,6 @@
 namespace host_tool
 {
 
-class HostIoInterface
-{
-  public:
-    virtual ~HostIoInterface() = default;
-
-    /**
-     * Attempt to read bytes from offset to the destination from the host
-     * memory device.
-     *
-     * @param[in] offset - offset into the host memory device.
-     * @param[in] length - the number of bytes to copy from source.
-     * @param[in] destination - where to write the bytes.
-     * @return true on success, false on failure (such as unable to initialize
-     * device).
-     */
-    virtual bool read(const std::size_t offset, const std::size_t length,
-                      void* const destination) = 0;
-
-    /**
-     * Attempt to write bytes from source to offset into the host memory device.
-     *
-     * @param[in] offset - offset into the host memory device.
-     * @param[in] length - the number of bytes to copy from source.
-     * @param[in] source - the souce of the bytes to copy to the memory device.
-     * @return true on success, false on failure (such as unable to initialize
-     * device).
-     */
-    virtual bool write(const std::size_t offset, const std::size_t length,
-                       const void* const source) = 0;
-};
-
 class DevMemDevice : public HostIoInterface
 {
   public:
diff --git a/tools/io_interface.hpp b/tools/io_interface.hpp
new file mode 100644
index 0000000..cdc81ad
--- /dev/null
+++ b/tools/io_interface.hpp
@@ -0,0 +1,39 @@
+#pragma once
+
+#include <cstdint>
+
+namespace host_tool
+{
+
+class HostIoInterface
+{
+  public:
+    virtual ~HostIoInterface() = default;
+
+    /**
+     * Attempt to read bytes from offset to the destination from the host
+     * memory device.
+     *
+     * @param[in] offset - offset into the host memory device.
+     * @param[in] length - the number of bytes to copy from source.
+     * @param[in] destination - where to write the bytes.
+     * @return true on success, false on failure (such as unable to initialize
+     * device).
+     */
+    virtual bool read(const std::size_t offset, const std::size_t length,
+                      void* const destination) = 0;
+
+    /**
+     * Attempt to write bytes from source to offset into the host memory device.
+     *
+     * @param[in] offset - offset into the host memory device.
+     * @param[in] length - the number of bytes to copy from source.
+     * @param[in] source - the souce of the bytes to copy to the memory device.
+     * @return true on success, false on failure (such as unable to initialize
+     * device).
+     */
+    virtual bool write(const std::size_t offset, const std::size_t length,
+                       const void* const source) = 0;
+};
+
+} // namespace host_tool
diff --git a/tools/test/io_mock.hpp b/tools/test/io_mock.hpp
index 4d18204..eddd6ff 100644
--- a/tools/test/io_mock.hpp
+++ b/tools/test/io_mock.hpp
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "io.hpp"
+#include "io_interface.hpp"
 
 #include <gmock/gmock.h>