diff --git a/Makefile b/Makefile
index 17f620c..56945be 100644
--- a/Makefile
+++ b/Makefile
@@ -5,15 +5,16 @@ include config.mk
 
 HDR = arg.h config.def.h proc.h reboot.h util.h
 LIB = \
-	util/agetcwd.o      \
-	util/apathmax.o     \
-	util/eprintf.o      \
-	util/estrtol.o      \
-	util/proc.o         \
-	util/putword.o      \
-	util/recurse.o      \
-	util/strlcat.o      \
-	util/strlcpy.o      \
+	util/agetcwd.o        \
+	util/apathmax.o       \
+	util/eprintf.o        \
+	util/estrtol.o        \
+	util/explicit_bzero.o \
+	util/proc.o           \
+	util/putword.o        \
+	util/recurse.o        \
+	util/strlcat.o        \
+	util/strlcpy.o        \
 	util/tty.o
 
 SRC = \
diff --git a/util.h b/util.h
index 76feaa9..416bb4c 100644
--- a/util.h
+++ b/util.h
@@ -12,6 +12,8 @@ void devtotty(int, int *, int *);
 void enprintf(int, const char *, ...);
 void eprintf(const char *, ...);
 long estrtol(const char *, int);
+#undef explicit_bzero
+void explicit_bzero(void *, size_t);
 void putword(const char *);
 void recurse(const char *, void (*)(const char *));
 #undef strlcat
diff --git a/util/explicit_bzero.c b/util/explicit_bzero.c
new file mode 100644
index 0000000..df00966
--- /dev/null
+++ b/util/explicit_bzero.c
@@ -0,0 +1,10 @@
+#include <string.h>
+#include "../util.h"
+
+static void *(*volatile explicit_memset)(void *, int, size_t) = memset;
+
+void
+explicit_bzero(void *b, size_t len)
+{
+	(*explicit_memset)(b, 0, len);
+}