diff --git a/Makefile b/Makefile
index 81f7911..26637d3 100644
--- a/Makefile
+++ b/Makefile
@@ -11,7 +11,6 @@ CFLAGS = -Wall -O3 -Werror -m32 -pthread -std=gnu11
 SHARED_OBJS = mdriver.o memlib.o fsecs.o fcyc.o clock.o ftimer.o list.o
 OBJS = $(SHARED_OBJS) mm.o
 MTOBJS = $(SHARED_OBJS) mmts.o
-BOOK_IMPL_OBJS = $(SHARED_OBJS) mm-book-implicit.o
 GBACK_IMPL_OBJS = $(SHARED_OBJS) mm-gback-implicit.o
 
 all: mdriver mdriver-ts
@@ -22,9 +21,6 @@ mdriver: $(OBJS)
 mdriver-ts: $(MTOBJS)
 	$(CC) $(CFLAGS) -o mdriver-ts $(MTOBJS)
 
-mdriver-book: $(BOOK_IMPL_OBJS)
-	$(CC) $(CFLAGS) -o $@ $(BOOK_IMPL_OBJS)
-
 mdriver-gback: $(GBACK_IMPL_OBJS)
 	$(CC) $(CFLAGS) -o $@ $(GBACK_IMPL_OBJS)