diff --git a/env.in b/env.in
index d89d202..e658bcb 100644
--- a/env.in
+++ b/env.in
@@ -18,11 +18,7 @@
 # License along with this program.  If not, see
 # <http://www.gnu.org/licenses/>.
 
-if test "$GUILE_LOAD_PATH" = ""; then
-  GUILE_LOAD_PATH=@abs_top_srcdir@
-else
-  GUILE_LOAD_PATH=@abs_top_srcdir@:$GUILE_LOAD_PATH
-fi
+GUILE_LOAD_PATH=@abs_top_srcdir@${GUILE_LOAD_PATH+:}$GUILE_LOAD_PATH
 
 if test "@abs_top_srcdir@" != "@abs_top_builddir@"; then
   GUILE_LOAD_PATH=@abs_top_builddir@:$GUILE_LOAD_PATH
@@ -30,29 +26,13 @@ fi
 
 GUILE_LOAD_PATH=@abs_top_builddir@/override:$GUILE_LOAD_PATH
 
-if test "$GUILE_LOAD_COMPILED_PATH" = ""; then
-  GUILE_LOAD_COMPILED_PATH=@abs_top_builddir@/override:@abs_top_builddir@
-else
-  GUILE_LOAD_COMPILED_PATH=@abs_top_builddir@/override:@abs_top_builddir@:$GUILE_LOAD_COMPILED_PATH
-fi
+GUILE_LOAD_COMPILED_PATH=@abs_top_builddir@/override:@abs_top_builddir@${GUILE_LOAD_COMPILED_PATH+:}$GUILE_LOAD_COMPILED_PATH
 
-if test "$GUILE_EXTENSIONS_PATH" = ""; then
-  GUILE_EXTENSIONS_PATH=@abs_top_builddir@/.libs
-else
-  GUILE_EXTENSIONS_PATH=@abs_top_builddir@/.libs:$GUILE_EXTENSIONS_PATH
-fi
+GUILE_EXTENSIONS_PATH=@abs_top_builddir@/.libs${GUILE_EXTENSIONS_PATH+:}$GUILE_EXTENSIONS_PATH
 
-if test "$LTDL_LIBRARY_PATH" = ""; then
-  LTDL_LIBRARY_PATH=@abs_top_builddir@/.libs
-else
-  LTDL_LIBRARY_PATH=@abs_top_builddir@/.libs:$LTDL_LIBRARY_PATH
-fi
+LTDL_LIBRARY_PATH=@abs_top_builddir@/.libs${LTDL_LIBRARY_PATH+:}$LTDL_LIBRARY_PATH
 
-if test "$PATH" = ""; then
-  PATH="@abs_top_srcdir@/bin"
-else
-  PATH="@abs_top_srcdir@/bin":$PATH
-fi
+PATH=@abs_top_srcdir@/bin${PATH+:}$PATH
 
 FIBERS_BUILD_DIR=@abs_top_builddir@