diff --git a/Makefile b/Makefile
index f61249c1..40e598b9 100644
--- a/Makefile
+++ b/Makefile
@@ -15,7 +15,7 @@ CHIBI_DOC_DEPENDENCIES ?= $(CHIBI_DEPENDENCIES) tools/chibi-doc
 
 GENSTATIC ?= ./tools/chibi-genstatic
 
-CHIBI ?= LD_LIBRARY_PATH=".:$(LD_LIBRARY_PATH)" DYLD_LIBRARY_PATH=".:$(DYLD_LIBRARY_PATH)" CHIBI_MODULE_PATH=lib ./chibi-scheme$(EXE)
+CHIBI ?= LD_LIBRARY_PATH=".:$(LD_LIBRARY_PATH)" DYLD_LIBRARY_PATH=".:$(DYLD_LIBRARY_PATH)" CHIBI_IGNORE_SYSTEM_PATH=1 CHIBI_MODULE_PATH=lib ./chibi-scheme$(EXE)
 CHIBI_DEPENDENCIES = ./chibi-scheme$(EXE)
 
 SNOW_CHIBI ?= tools/snow-chibi
diff --git a/eval.c b/eval.c
index 3d694914..84bc0473 100644
--- a/eval.c
+++ b/eval.c
@@ -486,13 +486,16 @@ static void sexp_init_eval_context_bytecodes (sexp ctx) {
 #endif
 
 void sexp_init_eval_context_globals (sexp ctx) {
+  const char* no_sys_path;
   const char* user_path;
   ctx = sexp_make_child_context(ctx, NULL);
 #if ! SEXP_USE_NATIVE_X86
   sexp_init_eval_context_bytecodes(ctx);
 #endif
   sexp_global(ctx, SEXP_G_MODULE_PATH) = SEXP_NULL;
-  sexp_add_path(ctx, sexp_default_module_path);
+  no_sys_path = getenv(SEXP_NO_SYSTEM_PATH_VAR);
+  if (!no_sys_path || strcmp(no_sys_path, "0")==0)
+    sexp_add_path(ctx, sexp_default_module_path);
   user_path = getenv(SEXP_MODULE_PATH_VAR);
   if (!user_path) user_path = sexp_default_user_module_path;
   sexp_add_path(ctx, user_path);
diff --git a/include/chibi/sexp.h b/include/chibi/sexp.h
index 151427f1..3f673a32 100644
--- a/include/chibi/sexp.h
+++ b/include/chibi/sexp.h
@@ -13,6 +13,7 @@ extern "C" {
 #endif
 
 #define SEXP_MODULE_PATH_VAR "CHIBI_MODULE_PATH"
+#define SEXP_NO_SYSTEM_PATH_VAR "CHIBI_IGNORE_SYSTEM_PATH"
 
 #include "chibi/features.h"
 #include "chibi/install.h"