diff --git a/pkgs/development/compilers/gcc-4.5/builder.sh b/pkgs/development/compilers/gcc-4.5/builder.sh
index 3be8e795162..be2a2b11c16 100644
--- a/pkgs/development/compilers/gcc-4.5/builder.sh
+++ b/pkgs/development/compilers/gcc-4.5/builder.sh
@@ -15,6 +15,12 @@ else
     EXTRA_LDFLAGS=""
 fi
 
+# GCC interprets empty paths as ".", which we don't want.
+if test -z "$CPATH"; then unset CPATH; fi
+if test -z "$LIBRARY_PATH"; then unset LIBRARY_PATH; fi
+echo "\$CPATH is \`$CPATH'"
+echo "\$LIBRARY_PATH is \`$LIBRARY_PATH'"
+
 if test "$noSysDirs" = "1"; then
 
     if test -e $NIX_GCC/nix-support/orig-libc; then
@@ -49,13 +55,6 @@ if test "$noSysDirs" = "1"; then
     done
 
     if test -n "$targetConfig"; then
-        # Cross-compiling, we need gcc not to read ./specs in order to build
-        # the g++ compiler (after the specs for the cross-gcc are created).
-        # Having LIBRARY_PATH= makes gcc read the specs from ., and the build
-        # breaks. Having this variable comes from the default.nix code to bring
-        # gcj in.
-        unset LIBRARY_PATH
-        unset CPATH
         if test -z "$crossStageStatic" -o -n "$crossMingw"; then
             EXTRA_FLAGS_TARGET="-g0 -O2 -B${libcCross}/lib -idirafter ${libcCross}/include"
             EXTRA_LDFLAGS_TARGET="-Wl,-L${libcCross}/lib"