diff --git a/pkgs/development/compilers/gcc-4.4/builder.sh b/pkgs/development/compilers/gcc-4.4/builder.sh
index c3ec4cec315..184bee74655 100644
--- a/pkgs/development/compilers/gcc-4.4/builder.sh
+++ b/pkgs/development/compilers/gcc-4.4/builder.sh
@@ -42,10 +42,10 @@ if test "$noSysDirs" = "1"; then
 
     # Setting $CPATH makes sure both `gcc' and `xgcc' find the C
     # library headers, regarless of the language being compiled.
-    export CPATH="$NIX_FIXINC_DUMMY:$CPATH"
+    export CPATH="$NIX_FIXINC_DUMMY${CPATH:+:}$CPATH"
 
     # Likewise, to help it find `crti.o' and similar files.
-    export LIBRARY_PATH="$glibc_libdir:$LIBRARY_PATH"
+    export LIBRARY_PATH="$glibc_libdir${LIBRARY_PATH:+:}$LIBRARY_PATH"
 
     echo "setting \$CPATH to \`$CPATH'"
     echo "setting \$LIBRARY_PATH to \`$LIBRARY_PATH'"