diff --git a/Makefile b/Makefile
index 4e0946319..e01421e2d 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 TESTS=quads mt-gcbench # MT_GCBench MT_GCBench2
-COLLECTORS=bdw semi mark-sweep parallel-mark-sweep
+COLLECTORS=bdw semi whippet parallel-whippet
 
 CC=gcc
 CFLAGS=-Wall -O2 -g -fno-strict-aliasing -Wno-unused -DNDEBUG
@@ -17,11 +17,11 @@ bdw-%: bdw.h conservative-roots.h %-types.h %.c
 semi-%: semi.h precise-roots.h large-object-space.h %-types.h heap-objects.h %.c
 	$(COMPILE) -DGC_SEMI -o $@ $*.c
 
-mark-sweep-%: mark-sweep.h precise-roots.h large-object-space.h serial-tracer.h assert.h debug.h %-types.h heap-objects.h %.c
-	$(COMPILE) -DGC_MARK_SWEEP -o $@ $*.c
+whippet-%: whippet.h precise-roots.h large-object-space.h serial-tracer.h assert.h debug.h %-types.h heap-objects.h %.c
+	$(COMPILE) -DGC_WHIPPET -o $@ $*.c
 
-parallel-mark-sweep-%: mark-sweep.h precise-roots.h large-object-space.h parallel-tracer.h assert.h debug.h %-types.h heap-objects.h %.c
-	$(COMPILE) -DGC_PARALLEL_MARK_SWEEP -o $@ $*.c
+parallel-whippet-%: whippet.h precise-roots.h large-object-space.h parallel-tracer.h assert.h debug.h %-types.h heap-objects.h %.c
+	$(COMPILE) -DGC_PARALLEL_WHIPPET -o $@ $*.c
 
 check: $(addprefix test-$(TARGET),$(TARGETS))
 
diff --git a/README.md b/README.md
index 21fd96c7a..2732566be 100644
--- a/README.md
+++ b/README.md
@@ -109,7 +109,7 @@ situate Whippet's performance in context:
  - `bdw.h`: The external BDW-GC conservative parallel stop-the-world
    mark-sweep segregated-fits collector with lazy sweeping.
  - `semi.h`: Semispace copying collector.
- - `mark-sweep.h`: The whippet collector.  Two different marking
+ - `whippet.h`: The whippet collector.  Two different marking
    implementations: single-threaded and parallel.
 
 ## Guile
diff --git a/gc.h b/gc.h
index 2c0c59de0..5d6268d9f 100644
--- a/gc.h
+++ b/gc.h
@@ -5,11 +5,11 @@
 #include "bdw.h"
 #elif defined(GC_SEMI)
 #include "semi.h"
-#elif defined(GC_MARK_SWEEP)
-#include "mark-sweep.h"
-#elif defined(GC_PARALLEL_MARK_SWEEP)
-#define GC_PARALLEL_MARK 1
-#include "mark-sweep.h"
+#elif defined(GC_WHIPPET)
+#include "whippet.h"
+#elif defined(GC_PARALLEL_WHIPPET)
+#define GC_PARALLEL_TRACE 1
+#include "whippet.h"
 #else
 #error unknown gc
 #endif
diff --git a/mark-sweep.h b/whippet.h
similarity index 99%
rename from mark-sweep.h
rename to whippet.h
index 98a3b30e1..48b1a53ee 100644
--- a/mark-sweep.h
+++ b/whippet.h
@@ -11,7 +11,7 @@
 #include "inline.h"
 #include "large-object-space.h"
 #include "precise-roots.h"
-#ifdef GC_PARALLEL_MARK
+#ifdef GC_PARALLEL_TRACE
 #include "parallel-tracer.h"
 #else
 #include "serial-tracer.h"