diff --git a/Makefile b/Makefile
index 05bf5079..6c80d105 100644
--- a/Makefile
+++ b/Makefile
@@ -20,12 +20,12 @@ REPL_ISSUE_TESTS = $(wildcard t/issue/*.sh)
 
 TEST_RUNNER = bin/picrin
 
-CFLAGS += -I./extlib/benz/include -Wall -Wextra $(CONTRIB_DEFS)
+CFLAGS += -I./extlib/benz/include -Wall -Wextra
 LDFLAGS += -lm
 
 prefix ?= /usr/local
 
-all: CFLAGS += -O2 -DNDEBUG=1
+all: CFLAGS += -O2 -flto -DNDEBUG=1
 all: bin/picrin
 
 debug: CFLAGS += -O0 -g
@@ -33,8 +33,9 @@ debug: bin/picrin
 
 include $(sort $(wildcard contrib/*/nitro.mk))
 
-bin/picrin: $(PICRIN_OBJS) $(CONTRIB_OBJS) lib/libbenz.so
-	$(CC) $(CFLAGS) -o $@ $(PICRIN_OBJS) $(CONTRIB_OBJS) lib/libbenz.so $(LDFLAGS)
+bin/picrin: CFLAGS += $(CONTRIB_DEFS)
+bin/picrin: $(PICRIN_OBJS) $(CONTRIB_OBJS) $(BENZ_OBJS)
+	$(CC) $(CFLAGS) -o $@ $(PICRIN_OBJS) $(CONTRIB_OBJS) $(BENZ_OBJS) $(LDFLAGS)
 
 src/load_piclib.c: $(CONTRIB_LIBS)
 	perl etc/mkloader.pl $(CONTRIB_LIBS) > $@
diff --git a/extlib/benz/file.c b/extlib/benz/file.c
index d828845d..9a844acd 100644
--- a/extlib/benz/file.c
+++ b/extlib/benz/file.c
@@ -186,7 +186,7 @@ int xfputs(pic_state *pic, const char *s, xFILE *stream) {
 }
 
 char *xfgets(pic_state *pic, char *s, int size, xFILE *stream) {
-  int c;
+  int c = 0;
   char *buf;
 
   xfflush(pic, NULL);
diff --git a/extlib/benz/include/picrin/setup.h b/extlib/benz/include/picrin/setup.h
index 49706ba7..34e36a49 100644
--- a/extlib/benz/include/picrin/setup.h
+++ b/extlib/benz/include/picrin/setup.h
@@ -131,10 +131,10 @@ typedef unsigned long uint32_t;
 
 #define PIC_FALLTHROUGH ((void)0)
 
-#if __cplusplus
+#if defined(__cplusplus)
 # define PIC_UNUSED(v)
 #elif __GNUC__ || __clang__
-# define PIC_UNUSED(v) __attribute__((unused)) v
+# define PIC_UNUSED(v) v __attribute__((unused))
 #else
 # define PIC_UNUSED(v) v
 #endif
diff --git a/extlib/benz/lib.c b/extlib/benz/lib.c
index e5bca1ad..c5bb5cad 100644
--- a/extlib/benz/lib.c
+++ b/extlib/benz/lib.c
@@ -61,7 +61,7 @@ void
 pic_make_library(pic_state *pic, const char *lib)
 {
   khash_t(ltable) *h = &pic->ltable;
-  const char *old_lib;
+  const char *old_lib = NULL;
   pic_value name, env, exports;
   int it;
   int ret;