diff --git a/Makefile b/Makefile
index ffbd1fa7..05579c84 100644
--- a/Makefile
+++ b/Makefile
@@ -9,6 +9,7 @@ LIBDIR   ?= $(PREFIX)/lib
 SOLIBDIR ?= $(PREFIX)/lib
 INCDIR   ?= $(PREFIX)/include/chibi
 MODDIR   ?= $(PREFIX)/share/chibi
+LIBDIR   ?= $(PREFIX)/lib/chibi
 
 DESTDIR ?=
 
@@ -49,7 +50,7 @@ endif
 
 all: chibi-scheme$(EXE)
 
-ifdef USE_BOEHM
+ifeq ($(USE_BOEHM),1)
 GCLDFLAGS := -lgc
 XCPPFLAGS := $(CPPFLAGS) -Iinclude -DUSE_BOEHM=1
 else
@@ -57,13 +58,19 @@ GCLDFLAGS :=
 XCPPFLAGS := $(CPPFLAGS) -Iinclude
 endif
 
+ifeq ($(USE_DL),0)
 XLDFLAGS  := $(LDFLAGS) $(GCLDFLAGS) -lm
+XCFLAGS   := -Wall -DUSE_DL=0 -g3 $(CFLAGS)
+else
+XLDFLAGS  := $(LDFLAGS) $(GCLDFLAGS) -ldl -lm
 XCFLAGS   := -Wall -g3 $(CFLAGS)
+endif
 
 INCLUDES = include/chibi/sexp.h include/chibi/config.h include/chibi/install.h
 
 include/chibi/install.h: Makefile
-	echo '#define sexp_module_dir "'$(MODDIR)'"' > $@
+	echo '#define sexp_so_extension "'$(SO)'"' > $@
+	echo '#define sexp_module_dir "'$(MODDIR)'"' >> $@
 
 sexp.o: sexp.c gc.c opt/bignum.c $(INCLUDES) Makefile
 	$(CC) -c $(XCPPFLAGS) $(XCFLAGS) $(CLIBFLAGS) -o $@ $<
diff --git a/eval.c b/eval.c
index 463b2cde..98f44e26 100644
--- a/eval.c
+++ b/eval.c
@@ -1999,9 +1999,31 @@ void sexp_warn_undefs (sexp ctx, sexp from, sexp to, sexp out) {
     }
 }
 
+#if USE_DL
+sexp sexp_load_dl (sexp ctx, sexp file, sexp env) {
+  sexp_proc2 init;
+  void *handle = dlopen(sexp_string_data(file), RTLD_LAZY);
+  if (! handle)
+    return sexp_compile_error(ctx, "couldn't load dynamic library", file);
+  init = dlsym(handle, "sexp_init_library");
+  if (! init) {
+    dlclose(handle);
+    return sexp_compile_error(ctx, "dynamic library has no sexp_init_library", file);
+  }
+  return init(ctx, env);
+}
+#endif
+
 sexp sexp_load (sexp ctx, sexp source, sexp env) {
   sexp tmp, out;
   sexp_gc_var4(ctx2, x, in, res);
+#if USE_DL
+  char *suffix = sexp_string_data(source)
+    + sexp_string_length(source) - strlen(sexp_so_extension);
+  if (strcmp(suffix, sexp_so_extension) == 0) {
+    res = sexp_load_dl(ctx, source, env);
+  } else {
+#endif
   sexp_gc_preserve4(ctx, ctx2, x, in, res);
   res = SEXP_VOID;
   in = sexp_open_input_file(ctx, source);
@@ -2027,12 +2049,15 @@ sexp sexp_load (sexp ctx, sexp source, sexp env) {
     if (x == SEXP_EOF)
       res = SEXP_VOID;
     sexp_close_port(ctx, in);
-#if USE_WARN_UNDEFS
-    if (sexp_oportp(out))
-      sexp_warn_undefs(ctx, sexp_env_bindings(env), tmp, out);
-#endif
   }
   sexp_gc_release4(ctx);
+#if USE_DL
+  }
+#endif
+#if USE_WARN_UNDEFS
+  if (sexp_oportp(out) && ! sexp_exceptionp(res))
+    sexp_warn_undefs(ctx, sexp_env_bindings(env), tmp, out);
+#endif
   return res;
 }
 
@@ -2272,17 +2297,17 @@ sexp sexp_apply (sexp ctx, sexp proc, sexp args) {
     stack[--offset] = sexp_car(ls);
   stack[top] = sexp_make_fixnum(len);
   top++;
-  sexp_context_top(ctx) = top + 3;
   stack[top++] = sexp_make_fixnum(0);
   stack[top++] = final_resumer;
   stack[top++] = sexp_make_fixnum(0);
+  sexp_context_top(ctx) = top;
   res = sexp_vm(ctx, proc);
   return res;
 }
 
 sexp sexp_compile (sexp ctx, sexp x) {
-  sexp_gc_var4(ast, ctx2, vec, res);
-  sexp_gc_preserve4(ctx, ast, ctx2, vec, res);
+  sexp_gc_var3(ast, vec, res);
+  sexp_gc_preserve3(ctx, ast, vec, res);
   ast = analyze(ctx, x);
   if (sexp_exceptionp(ast)) {
     res = ast;
@@ -2294,7 +2319,7 @@ sexp sexp_compile (sexp ctx, sexp x) {
     res = sexp_make_procedure(ctx, sexp_make_fixnum(0), sexp_make_fixnum(0),
                               res, vec);
   }
-  sexp_gc_release4(ctx);
+  sexp_gc_release3(ctx);
   return res;
 }
 
diff --git a/include/chibi/config.h b/include/chibi/config.h
index 834c3ea2..7436a2c0 100644
--- a/include/chibi/config.h
+++ b/include/chibi/config.h
@@ -5,6 +5,9 @@
 /* uncomment this to disable the module system */
 /* #define USE_MODULES 0 */
 
+/* uncomment this to disable dynamic loading */
+/* #define USE_DL 0 */
+
 /* uncomment this to use the Boehm conservative GC */
 /* #define USE_BOEHM 1 */
 
@@ -67,6 +70,14 @@
 #define USE_MODULES 1
 #endif
 
+#ifndef USE_DL
+#ifdef PLAN9
+#define USE_DL 0
+#else
+#define USE_DL 1
+#endif
+#endif
+
 #ifndef USE_BOEHM
 #define USE_BOEHM 0
 #endif
diff --git a/include/chibi/sexp.h b/include/chibi/sexp.h
index 3b0c9183..001217a5 100644
--- a/include/chibi/sexp.h
+++ b/include/chibi/sexp.h
@@ -11,6 +11,10 @@
 #include <ctype.h>
 #include <stdio.h>
 
+#if USE_DL
+#include <dlfcn.h>
+#endif
+
 #ifdef PLAN9
 #include <u.h>
 #include <libc.h>
@@ -555,6 +559,9 @@ SEXP_API sexp sexp_make_integer(sexp ctx, sexp_sint_t x);
 #define sexp_bignum_length(x)         ((x)->value.bignum.length)
 #define sexp_bignum_data(x)           ((x)->value.bignum.data)
 
+#define sexp_dllib_file(x)            ((x)->value.dllib.file)
+#define sexp_dllib_handle(x)          ((x)->value.dllib.handle)
+
 /****************************** arithmetic ****************************/
 
 #define sexp_fx_add(a, b) ((sexp)(((sexp_sint_t)a)+((sexp_sint_t)b)-SEXP_FIXNUM_TAG))
diff --git a/main.c b/main.c
index 7f05c55e..7ded21c5 100644
--- a/main.c
+++ b/main.c
@@ -50,10 +50,8 @@ sexp find_module_file (sexp ctx, char *file) {
 
 sexp sexp_load_module_file (sexp ctx, char *file, sexp env) {
   sexp res = SEXP_VOID;
-  sexp_gc_var(ctx, path, s_path);
-  sexp_gc_var(ctx, irr, s_irr);
-  sexp_gc_preserve(ctx, path, s_path);
-  sexp_gc_preserve(ctx, irr, s_irr);
+  sexp_gc_var2(path, irr);
+  sexp_gc_preserve2(ctx, path, irr);
   path = find_module_file(ctx, file);
   if (! sexp_stringp(path)) {
     path = sexp_c_string(ctx, chibi_module_dir, -1);
@@ -67,32 +65,32 @@ sexp sexp_load_module_file (sexp ctx, char *file, sexp env) {
   } else {
     res = sexp_load(ctx, path, env);
   }
-  sexp_gc_release(ctx, path, s_path);
+  sexp_gc_release2(ctx);
   return res;
 }
 
 sexp sexp_init_environments (sexp ctx) {
   sexp res, env;
-  sexp_gc_var(ctx, confenv, s_confenv);
+  sexp_gc_var1(confenv);
   env = sexp_context_env(ctx);
   res = sexp_load_module_file(ctx, sexp_init_file, env);
   if (! sexp_exceptionp(res)) {
     res = SEXP_UNDEF;
-    sexp_gc_preserve(ctx, confenv, s_confenv);
+    sexp_gc_preserve1(ctx, confenv);
     confenv = sexp_make_env(ctx);
     sexp_env_copy(ctx, confenv, env, SEXP_FALSE);
     sexp_load_module_file(ctx, sexp_config_file, confenv);
     env_define(ctx, env, sexp_intern(ctx, "*config-env*"), confenv);
     env_define(ctx, confenv, sexp_intern(ctx, "*config-env*"), confenv);
-    sexp_gc_release(ctx, confenv, s_confenv);
+    sexp_gc_release1(ctx);
   }
   return res;
 }
 
 void repl (sexp ctx) {
   sexp tmp, res, env, in, out, err;
-  sexp_gc_var(ctx, obj, s_obj);
-  sexp_gc_preserve(ctx, obj, s_obj);
+  sexp_gc_var1(obj);
+  sexp_gc_preserve1(ctx, obj);
   env = sexp_context_env(ctx);
   sexp_context_tracep(ctx) = 1;
   in = sexp_eval_string(ctx, "(current-input-port)", env);
@@ -120,18 +118,16 @@ void repl (sexp ctx) {
       }
     }
   }
-  sexp_gc_release(ctx, obj, s_obj);
+  sexp_gc_release1(ctx);
 }
 
 void run_main (int argc, char **argv) {
   sexp env, out=NULL, res=SEXP_VOID, ctx;
   sexp_uint_t i, quit=0, init_loaded=0;
-  sexp_gc_var(ctx, str, s_str);
-  sexp_gc_var(ctx, confenv, s_confenv);
+  sexp_gc_var1(str);
 
   ctx = sexp_make_context(NULL, NULL, NULL);
-  sexp_gc_preserve(ctx, str, s_str);
-  sexp_gc_preserve(ctx, confenv, s_confenv);
+  sexp_gc_preserve1(ctx, str);
   env = sexp_context_env(ctx);
   out = sexp_eval_string(ctx, "(current-output-port)", env);
 
@@ -185,7 +181,7 @@ void run_main (int argc, char **argv) {
       repl(ctx);
   }
 
-  sexp_gc_release(ctx, str, s_str);
+  sexp_gc_release1(ctx);
 }
 
 int main (int argc, char **argv) {