diff --git a/src/impl/list_ports/list_ports_linux.cc b/src/impl/list_ports/list_ports_linux.cc
index 14c154b..cb5e343 100644
--- a/src/impl/list_ports/list_ports_linux.cc
+++ b/src/impl/list_ports/list_ports_linux.cc
@@ -1,3 +1,5 @@
+#if defined(__linux__)
+
 /*
  * Copyright (c) 2014 Craig Lilley <cralilley@gmail.com>
  * This software is made available under the terms of the MIT licence.
@@ -329,3 +331,5 @@ serial::list_ports()
 
     return results;
 }
+
+#endif // defined(__linux__)
diff --git a/src/impl/list_ports/list_ports_osx.cc b/src/impl/list_ports/list_ports_osx.cc
index bf819d4..29da120 100644
--- a/src/impl/list_ports/list_ports_osx.cc
+++ b/src/impl/list_ports/list_ports_osx.cc
@@ -1,3 +1,5 @@
+#if defined(__APPLE__)
+
 #include <sys/param.h>
 #include <stdint.h>
 
@@ -278,4 +280,6 @@ serial::list_ports(void)
     }
 
     return devices_found;
-}
\ No newline at end of file
+}
+
+#endif // defined(__APPLE__)
diff --git a/src/impl/list_ports/list_ports_win.cc b/src/impl/list_ports/list_ports_win.cc
index e792f93..4e6e0cf 100644
--- a/src/impl/list_ports/list_ports_win.cc
+++ b/src/impl/list_ports/list_ports_win.cc
@@ -1,3 +1,5 @@
+#if defined(_WIN32)
+
 /*
  * Copyright (c) 2014 Craig Lilley <cralilley@gmail.com>
  * This software is made available under the terms of the MIT licence.
@@ -125,3 +127,5 @@ serial::list_ports()
 
 	return devices_found;
 }
+
+#endif // #if defined(_WIN32)