diff --git a/etc/bashrc b/etc/bashrc
index ce10b39e78..3b001711bc 100644
--- a/etc/bashrc
+++ b/etc/bashrc
@@ -77,6 +77,12 @@ export WM_PROJECT_USER_DIR=$HOME/$WM_PROJECT/$USER-$WM_PROJECT_VERSION
 export WM_THIRD_PARTY_DIR=$WM_PROJECT_INST_DIR/ThirdParty
 
 
+# Operating System/Platform
+# ~~~~~~~~~~~~~~~~~~~~~~~~~
+# WM_OS = Unix | ????
+: ${WM_OS:=Unix}; export WM_OS
+
+
 # Compiler: set to Gcc, Gcc43 or Icc (for Intel's icc)
 # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 : ${WM_COMPILER:=Gcc}; export WM_COMPILER
diff --git a/etc/cshrc b/etc/cshrc
index a46cf3ee47..034a5bfbfa 100644
--- a/etc/cshrc
+++ b/etc/cshrc
@@ -71,6 +71,12 @@ setenv WM_PROJECT_USER_DIR $HOME/$WM_PROJECT/$LOGNAME-$WM_PROJECT_VERSION
 setenv WM_THIRD_PARTY_DIR $WM_PROJECT_INST_DIR/ThirdParty
 
 
+# Operating System/Platform
+# ~~~~~~~~~~~~~~~~~~~~~~~~~
+# WM_OS = Unix | ????
+if ( ! $?WM_OS ) setenv WM_OS Unix
+
+
 # Compiler: set to Gcc, Gcc43 or Icc (for Intel's icc)
 # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 if ( ! $?WM_COMPILER ) setenv WM_COMPILER Gcc