diff --git a/configure.ac b/configure.ac
index 2418b988f..b04bee072 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,9 +43,12 @@ elif test "$OS" = "haiku"; then
 elif test "$OS" = "freeb"; then
   AC_MSG_NOTICE([OS FreeBSD detected])
   AC_DEFINE([FREEBSD], [], [Compiling on FreeBSD])
-else
+elif test "$OS" = "linux"; then
   AC_MSG_NOTICE([OS Linux detected])
   AC_DEFINE([LINUX], [], [Compiling on Linux])
+else
+  AC_MSG_NOTICE([OS not detected])
+  AC_DEFINE([UNKNOWN], [], [Compiling on Unknown])
 fi
 
 AM_INIT_AUTOMAKE
diff --git a/src/command.cpp b/src/command.cpp
index f8e235677..9a6b11b7f 100644
--- a/src/command.cpp
+++ b/src/command.cpp
@@ -508,8 +508,10 @@ int handleVersion (std::string &outs)
       << "haiku"
 #elif defined (FREEBSD)
       << "freebsd"
-#else
+#elif defined (LINUX)
       << "linux"
+#else
+      << "unknown"
 #endif
 
 #ifdef HAVE_LIBNCURSES