diff -ru3 gcc-3.3.6-old/gcc/cppdefault.c gcc-3.3.6/gcc/cppdefault.c
--- gcc-3.3.6-old/gcc/cppdefault.c	2003-11-07 02:13:31.000000000 +0300
+++ gcc-3.3.6/gcc/cppdefault.c	2016-09-02 16:00:03.492484016 +0300
@@ -26,6 +26,10 @@
 #include "system.h"
 #include "cppdefault.h"
 
+#undef LOCAL_INCLUDE_DIR
+#undef SYSTEM_INCLUDE_DIR
+#undef STANDARD_INCLUDE_DIR
+
 const struct default_include cpp_include_defaults[]
 #ifdef INCLUDE_DEFAULTS
 = INCLUDE_DEFAULTS;
diff -ru3 gcc-3.3.6-old/gcc/gcc.c gcc-3.3.6/gcc/gcc.c
--- gcc-3.3.6-old/gcc/gcc.c	2004-04-01 20:55:17.000000000 +0400
+++ gcc-3.3.6/gcc/gcc.c	2016-09-02 16:01:24.843520114 +0300
@@ -6130,10 +6130,6 @@
 		      NULL, PREFIX_PRIORITY_LAST, 0, NULL, 1);
 	}
 
-      add_sysrooted_prefix (&startfile_prefixes, standard_startfile_prefix_1,
-			    "BINUTILS", PREFIX_PRIORITY_LAST, 0, NULL, 1);
-      add_sysrooted_prefix (&startfile_prefixes, standard_startfile_prefix_2,
-			    "BINUTILS", PREFIX_PRIORITY_LAST, 0, NULL, 1);
 #if 0 /* Can cause surprises, and one can use -B./ instead.  */
       add_prefix (&startfile_prefixes, "./", NULL,
 		  PREFIX_PRIORITY_LAST, 1, NULL, 0);
diff -ru3 gcc-3.3.6-old/gcc/Makefile.in gcc-3.3.6/gcc/Makefile.in
--- gcc-3.3.6-old/gcc/Makefile.in	2004-04-01 20:55:23.000000000 +0400
+++ gcc-3.3.6/gcc/Makefile.in	2016-09-02 16:00:03.493484017 +0300
@@ -260,7 +260,11 @@
 PARTITION_H = $(srcdir)/../include/partition.h
 
 # Default native SYSTEM_HEADER_DIR, to be overridden by targets.
-NATIVE_SYSTEM_HEADER_DIR = /usr/include
+# Nix: we override NATIVE_SYSTEM_HEADER_DIR in order to prevent
+# `fixinc' from fixing header files in /usr/include.  However,
+# NATIVE_SYSTEM_HEADER_DIR must point to an existing directory, so set
+# it to some dummy directory.
+NATIVE_SYSTEM_HEADER_DIR = $(NIX_FIXINC_DUMMY)
 # Default cross SYSTEM_HEADER_DIR, to be overridden by targets.
 CROSS_SYSTEM_HEADER_DIR = @CROSS_SYSTEM_HEADER_DIR@
 
@@ -2201,7 +2205,7 @@
   -DGPLUSPLUS_INCLUDE_DIR=\"$(gcc_gxx_include_dir)\" \
   -DGPLUSPLUS_TOOL_INCLUDE_DIR=\"$(gcc_gxx_include_dir)/$(target_alias)\" \
   -DGPLUSPLUS_BACKWARD_INCLUDE_DIR=\"$(gcc_gxx_include_dir)/backward\" \
-  -DLOCAL_INCLUDE_DIR=\"$(local_includedir)\" \
+  -DLOCAL_INCLUDE_DIR=\"/no-such-dir\" \
   -DCROSS_INCLUDE_DIR=\"$(CROSS_SYSTEM_HEADER_DIR)\" \
   -DTOOL_INCLUDE_DIR=\"$(gcc_tooldir)/include\" \
   @TARGET_SYSTEM_ROOT_DEFINE@