diff --git a/nonnixshellrc b/nonnixshellrc
index 57f5998..35fce58 100644
--- a/nonnixshellrc
+++ b/nonnixshellrc
@@ -21,7 +21,11 @@ add_to PATH ~/.cabal/bin
 
 add_myprefix_to LD_LIBRARY_PATH lib
 
-add_myprefix_to MANPATH share/man
+if [ -z "$MANPATH" ]; then
+  export MANPATH="$MYPREFIX/share/man:"
+else
+  add_myprefix_to MANPATH share/man
+fi
 
 add_myprefix_to PKG_CONFIG_PATH lib/pkgconfig