diff --git a/Makefile b/Makefile
index 7440a9d..49fb35c 100644
--- a/Makefile
+++ b/Makefile
@@ -3,11 +3,15 @@
 .SUFFIXES:
 .SUFFIXES: .c .o .test
 CC=cc
+TEST_WRAPPER=valgrind --exit-on-first-error=yes
 
-CFLAGS=-Wall -std=c89 -Werror -pedantic -fPIC -g -Iinclude -I.
+CFLAGS=-Wall -std=c89 -Werror -pedantic -fPIC -g -Iinclude -I. -Wno-unused-function -Wno-unused-variable ${EXTRACFLAGS}
 
 tests: string_tests htable_tests
 
+with_valgrind:
+	make EXTRACFLAGS=-DUNS_VALGRIND
+
 COMMON_OBJECTS=uns.o
 
 uns.o: uns.c include/uns.h
diff --git a/cheney_c89.c b/cheney_c89.c
index d1b499d..b94fd55 100644
--- a/cheney_c89.c
+++ b/cheney_c89.c
@@ -16,6 +16,16 @@
 */
 #include <stdio.h>
 
+#ifdef UNS_VALGRIND
+# include <valgrind/valgrind.h>
+# define REDZONE 16
+#else
+# define REDZONE 0
+# define VALGRIND_CREATE_MEMPOOL(pool, rzB, is_zeroed) (void)0
+# define VALGRIND_DESTROY_MEMPOOL(pool) (void)0
+# define VALGRIND_MEMPOOL_ALLOC(pool, ptr, siz) (void)0
+#endif
+
 #include <stdlib.h>
 #include <limits.h>
 #include <assert.h>
@@ -186,7 +196,7 @@ static void hdr_write_direct(struct hdr *hdr, unsigned char *p)
   */
 static int enough_space(struct ctx *ctx, uns_sword bytes)
 {
-	return ctx->tospace_end - ctx->tospace_alloc >= bytes + HDR_LEN;
+	return ctx->tospace_end - ctx->tospace_alloc >= bytes + HDR_LEN + REDZONE;
 }
 
 /** Allocate region without bounds checking.
@@ -215,8 +225,10 @@ static void *raw_alloc(struct ctx *ctx, uns_sword len, int is_record)
 	assert(enough_space(ctx, len));
 
 	p = ctx->tospace_alloc;
+	VALGRIND_MEMPOOL_ALLOC(ctx->tospace, p, len);
+
 	hdr_write_direct(&hdr, p);
-	ctx->tospace_alloc += len;
+	ctx->tospace_alloc += len + REDZONE;
 
 	return p + HDR_LEN;
 }
@@ -342,7 +354,7 @@ static void relocate_everything(Uns_GC gc)
 
 		if (hdr.typ == RECORD)
 			scan_record(ctx, scanptr, (size_t)hdr.len/sizeof(void*));
-		scanptr += hdr.len;
+		scanptr += hdr.len + REDZONE;
 	}
 
 }
@@ -363,6 +375,7 @@ int uns_cheney_c89_collect(Uns_GC gc)
 	 */
 	assert(newlen >= fromspace_lim - fromspace);
 	ctx->tospace = malloc(newlen);
+	VALGRIND_CREATE_MEMPOOL(ctx->tospace, REDZONE, 0);
 	if (!ctx->tospace) {
 		ctx->tospace = fromspace;
 		return 1;
@@ -374,6 +387,7 @@ int uns_cheney_c89_collect(Uns_GC gc)
 
 	relocate_everything(gc);
 
+	VALGRIND_DESTROY_MEMPOOL(fromspace);
 	free(fromspace);
 
 	ctx->stats.usage_after = ctx->tospace_alloc - ctx->tospace;
@@ -446,6 +460,7 @@ int uns_cheney_c89_init(Uns_GC gc, size_t heap_size)
 
 	uns_deinit(gc);
 	ctx->tospace_alloc = ctx->tospace = malloc(heap_size);
+	VALGRIND_CREATE_MEMPOOL(ctx->tospace, REDZONE, 0);
 	if (!ctx->tospace) {
 		free(ctx);
 		return 0;
diff --git a/gen_tests.sh b/gen_tests.sh
index 16f1419..114dbf2 100755
--- a/gen_tests.sh
+++ b/gen_tests.sh
@@ -21,8 +21,8 @@ gen_test() { # test_name, collector_name, exec_deps, obj_file_deps
 
 	echo "
 $TARGET: $DEPS
-	\${CC} \${LDFLAGS} $DEPS $TARGET
-	./valgrind ./$TARGET
+	\${CC} \${TEST_LDFLAGS} $DEPS -o $TARGET
+	\${TEST_WRAPPER} ./$TARGET
 "
 
 	TEST_TARGETS="$TEST_TARGETS $TARGET"
@@ -72,7 +72,7 @@ gen_lisp_test() { #collector_name, exec_deps
 $SHIM_OBJ: $OBJDEPS
 
 $TARGET: $DEPS
-	\${CC} \${LDFLAGS} $DEPS -o $TARGET
+	\${CC} \${TEST_LDFLAGS} $DEPS -o $TARGET
 "
 
 	TEST_TARGETS="$TEST_TARGETS $TARGET"