diff --git a/Makefile.in b/Makefile.in
index 53ebe32e..04ce288a 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -99,6 +99,7 @@ C_SRCS := $(srcroot)src/jemalloc.c \
 	$(srcroot)src/extent_mmap.c \
 	$(srcroot)src/hash.c \
 	$(srcroot)src/large.c \
+	$(srcroot)src/malloc_io.c \
 	$(srcroot)src/mutex.c \
 	$(srcroot)src/nstime.c \
 	$(srcroot)src/pages.c \
@@ -110,7 +111,6 @@ C_SRCS := $(srcroot)src/jemalloc.c \
 	$(srcroot)src/tcache.c \
 	$(srcroot)src/ticker.c \
 	$(srcroot)src/tsd.c \
-	$(srcroot)src/util.c \
 	$(srcroot)src/witness.c
 ifeq ($(enable_zone_allocator), 1)
 C_SRCS += $(srcroot)src/zone.c
@@ -147,8 +147,8 @@ ifeq (1, $(link_whole_archive))
 C_UTIL_INTEGRATION_SRCS :=
 C_UTIL_CPP_SRCS :=
 else
-C_UTIL_INTEGRATION_SRCS := $(srcroot)src/nstime.c $(srcroot)src/util.c
-C_UTIL_CPP_SRCS := $(srcroot)src/nstime.c $(srcroot)src/util.c
+C_UTIL_INTEGRATION_SRCS := $(srcroot)src/nstime.c $(srcroot)src/malloc_io.c
+C_UTIL_CPP_SRCS := $(srcroot)src/nstime.c $(srcroot)src/malloc_io.c
 endif
 TESTS_UNIT := \
 	$(srcroot)test/unit/a0.c \
@@ -165,6 +165,7 @@ TESTS_UNIT := \
 	$(srcroot)test/unit/junk_alloc.c \
 	$(srcroot)test/unit/junk_free.c \
 	$(srcroot)test/unit/mallctl.c \
+	$(srcroot)test/unit/malloc_io.c \
 	$(srcroot)test/unit/math.c \
 	$(srcroot)test/unit/mq.c \
 	$(srcroot)test/unit/mtx.c \
@@ -193,7 +194,6 @@ TESTS_UNIT := \
 	$(srcroot)test/unit/ticker.c \
 	$(srcroot)test/unit/nstime.c \
 	$(srcroot)test/unit/tsd.c \
-	$(srcroot)test/unit/util.c \
 	$(srcroot)test/unit/witness.c \
 	$(srcroot)test/unit/zero.c
 ifeq (@enable_prof@, 1)
diff --git a/include/jemalloc/internal/assert.h b/include/jemalloc/internal/assert.h
index b9ab813e..be4d45b3 100644
--- a/include/jemalloc/internal/assert.h
+++ b/include/jemalloc/internal/assert.h
@@ -1,3 +1,6 @@
+#include "jemalloc/internal/malloc_io.h"
+#include "jemalloc/internal/util.h"
+
 /*
  * Define a custom assert() in order to reduce the chances of deadlock during
  * assertion failure.
@@ -43,4 +46,11 @@
 } while (0)
 #endif
 
-
+/* Use to assert a particular configuration, e.g., cassert(config_debug). */
+#ifndef cassert
+#define cassert(c) do {							\
+	if (unlikely(!(c))) {						\
+		not_reached();						\
+	}								\
+} while (0)
+#endif
diff --git a/include/jemalloc/internal/util_inlines.h b/include/jemalloc/internal/bit_util.h
similarity index 67%
rename from include/jemalloc/internal/util_inlines.h
rename to include/jemalloc/internal/bit_util.h
index c09bd6da..8d078a8a 100644
--- a/include/jemalloc/internal/util_inlines.h
+++ b/include/jemalloc/internal/bit_util.h
@@ -1,22 +1,9 @@
-#ifndef JEMALLOC_INTERNAL_UTIL_INLINES_H
-#define JEMALLOC_INTERNAL_UTIL_INLINES_H
+#ifndef JEMALLOC_INTERNAL_BIT_UTIL_H
+#define JEMALLOC_INTERNAL_BIT_UTIL_H
 
-#ifndef JEMALLOC_ENABLE_INLINE
-unsigned	ffs_llu(unsigned long long bitmap);
-unsigned	ffs_lu(unsigned long bitmap);
-unsigned	ffs_u(unsigned bitmap);
-unsigned	ffs_zu(size_t bitmap);
-unsigned	ffs_u64(uint64_t bitmap);
-unsigned	ffs_u32(uint32_t bitmap);
-uint64_t	pow2_ceil_u64(uint64_t x);
-uint32_t	pow2_ceil_u32(uint32_t x);
-size_t	pow2_ceil_zu(size_t x);
-unsigned	lg_floor(size_t x);
-void	set_errno(int errnum);
-int	get_errno(void);
-#endif
+#include "jemalloc/internal/assert.h"
 
-#if (defined(JEMALLOC_ENABLE_INLINE) || defined(JEMALLOC_UTIL_C_))
+#define BIT_UTIL_INLINE static inline
 
 /* Sanity check. */
 #if !defined(JEMALLOC_INTERNAL_FFSLL) || !defined(JEMALLOC_INTERNAL_FFSL) \
@@ -24,22 +11,23 @@ int	get_errno(void);
 #  error JEMALLOC_INTERNAL_FFS{,L,LL} should have been defined by configure
 #endif
 
-JEMALLOC_ALWAYS_INLINE unsigned
+
+BIT_UTIL_INLINE unsigned
 ffs_llu(unsigned long long bitmap) {
 	return JEMALLOC_INTERNAL_FFSLL(bitmap);
 }
 
-JEMALLOC_ALWAYS_INLINE unsigned
+BIT_UTIL_INLINE unsigned
 ffs_lu(unsigned long bitmap) {
 	return JEMALLOC_INTERNAL_FFSL(bitmap);
 }
 
-JEMALLOC_ALWAYS_INLINE unsigned
+BIT_UTIL_INLINE unsigned
 ffs_u(unsigned bitmap) {
 	return JEMALLOC_INTERNAL_FFS(bitmap);
 }
 
-JEMALLOC_ALWAYS_INLINE unsigned
+BIT_UTIL_INLINE unsigned
 ffs_zu(size_t bitmap) {
 #if LG_SIZEOF_PTR == LG_SIZEOF_INT
 	return ffs_u(bitmap);
@@ -52,7 +40,7 @@ ffs_zu(size_t bitmap) {
 #endif
 }
 
-JEMALLOC_ALWAYS_INLINE unsigned
+BIT_UTIL_INLINE unsigned
 ffs_u64(uint64_t bitmap) {
 #if LG_SIZEOF_LONG == 3
 	return ffs_lu(bitmap);
@@ -63,7 +51,7 @@ ffs_u64(uint64_t bitmap) {
 #endif
 }
 
-JEMALLOC_ALWAYS_INLINE unsigned
+BIT_UTIL_INLINE unsigned
 ffs_u32(uint32_t bitmap) {
 #if LG_SIZEOF_INT == 2
 	return ffs_u(bitmap);
@@ -73,7 +61,7 @@ ffs_u32(uint32_t bitmap) {
 	return ffs_u(bitmap);
 }
 
-JEMALLOC_INLINE uint64_t
+BIT_UTIL_INLINE uint64_t
 pow2_ceil_u64(uint64_t x) {
 	x--;
 	x |= x >> 1;
@@ -86,7 +74,7 @@ pow2_ceil_u64(uint64_t x) {
 	return x;
 }
 
-JEMALLOC_INLINE uint32_t
+BIT_UTIL_INLINE uint32_t
 pow2_ceil_u32(uint32_t x) {
 	x--;
 	x |= x >> 1;
@@ -99,7 +87,7 @@ pow2_ceil_u32(uint32_t x) {
 }
 
 /* Compute the smallest power of 2 that is >= x. */
-JEMALLOC_INLINE size_t
+BIT_UTIL_INLINE size_t
 pow2_ceil_zu(size_t x) {
 #if (LG_SIZEOF_PTR == 3)
 	return pow2_ceil_u64(x);
@@ -109,10 +97,9 @@ pow2_ceil_zu(size_t x) {
 }
 
 #if (defined(__i386__) || defined(__amd64__) || defined(__x86_64__))
-JEMALLOC_INLINE unsigned
+BIT_UTIL_INLINE unsigned
 lg_floor(size_t x) {
 	size_t ret;
-
 	assert(x != 0);
 
 	asm ("bsr %1, %0"
@@ -123,7 +110,7 @@ lg_floor(size_t x) {
 	return (unsigned)ret;
 }
 #elif (defined(_MSC_VER))
-JEMALLOC_INLINE unsigned
+BIT_UTIL_INLINE unsigned
 lg_floor(size_t x) {
 	unsigned long ret;
 
@@ -140,7 +127,7 @@ lg_floor(size_t x) {
 	return (unsigned)ret;
 }
 #elif (defined(JEMALLOC_HAVE_BUILTIN_CLZ))
-JEMALLOC_INLINE unsigned
+BIT_UTIL_INLINE unsigned
 lg_floor(size_t x) {
 	assert(x != 0);
 
@@ -153,7 +140,7 @@ lg_floor(size_t x) {
 #endif
 }
 #else
-JEMALLOC_INLINE unsigned
+BIT_UTIL_INLINE unsigned
 lg_floor(size_t x) {
 	assert(x != 0);
 
@@ -173,25 +160,6 @@ lg_floor(size_t x) {
 }
 #endif
 
-/* Set error code. */
-JEMALLOC_INLINE void
-set_errno(int errnum) {
-#ifdef _WIN32
-	SetLastError(errnum);
-#else
-	errno = errnum;
-#endif
-}
+#undef BIT_UTIL_INLINE
 
-/* Get last error code. */
-JEMALLOC_INLINE int
-get_errno(void) {
-#ifdef _WIN32
-	return GetLastError();
-#else
-	return errno;
-#endif
-}
-#endif
-
-#endif /* JEMALLOC_INTERNAL_UTIL_INLINES_H */
+#endif /* JEMALLOC_INTERNAL_BIT_UTIL_H */
diff --git a/include/jemalloc/internal/jemalloc_internal.h.in b/include/jemalloc/internal/jemalloc_internal.h.in
index f18acabb..09eda5ec 100644
--- a/include/jemalloc/internal/jemalloc_internal.h.in
+++ b/include/jemalloc/internal/jemalloc_internal.h.in
@@ -204,7 +204,11 @@ static const bool have_thp =
 /* HERMETIC HEADERS */
 /******************************************************************************/
 
+#include "jemalloc/internal/assert.h"
 #include "jemalloc/internal/atomic.h"
+#include "jemalloc/internal/bit_util.h"
+#include "jemalloc/internal/malloc_io.h"
+#include "jemalloc/internal/util.h"
 
 /******************************************************************************/
 /* TYPES */
@@ -382,7 +386,6 @@ typedef unsigned szind_t;
 #endif
 
 #include "jemalloc/internal/nstime_types.h"
-#include "jemalloc/internal/util_types.h"
 #include "jemalloc/internal/spin_types.h"
 #include "jemalloc/internal/prng_types.h"
 #include "jemalloc/internal/ticker_types.h"
@@ -490,7 +493,6 @@ void	jemalloc_postfork_parent(void);
 void	jemalloc_postfork_child(void);
 
 #include "jemalloc/internal/nstime_externs.h"
-#include "jemalloc/internal/util_externs.h"
 #include "jemalloc/internal/ckh_externs.h"
 #include "jemalloc/internal/stats_externs.h"
 #include "jemalloc/internal/ctl_externs.h"
@@ -513,7 +515,6 @@ void	jemalloc_postfork_child(void);
 /* INLINES */
 /******************************************************************************/
 
-#include "jemalloc/internal/util_inlines.h"
 #include "jemalloc/internal/spin_inlines.h"
 #include "jemalloc/internal/prng_inlines.h"
 #include "jemalloc/internal/ticker_inlines.h"
diff --git a/include/jemalloc/internal/malloc_io.h b/include/jemalloc/internal/malloc_io.h
new file mode 100644
index 00000000..7ff3d5b1
--- /dev/null
+++ b/include/jemalloc/internal/malloc_io.h
@@ -0,0 +1,63 @@
+#ifndef JEMALLOC_INTERNAL_MALLOC_IO_H
+#define JEMALLOC_INTERNAL_MALLOC_IO_H
+
+#ifdef _WIN32
+#  ifdef _WIN64
+#    define FMT64_PREFIX "ll"
+#    define FMTPTR_PREFIX "ll"
+#  else
+#    define FMT64_PREFIX "ll"
+#    define FMTPTR_PREFIX ""
+#  endif
+#  define FMTd32 "d"
+#  define FMTu32 "u"
+#  define FMTx32 "x"
+#  define FMTd64 FMT64_PREFIX "d"
+#  define FMTu64 FMT64_PREFIX "u"
+#  define FMTx64 FMT64_PREFIX "x"
+#  define FMTdPTR FMTPTR_PREFIX "d"
+#  define FMTuPTR FMTPTR_PREFIX "u"
+#  define FMTxPTR FMTPTR_PREFIX "x"
+#else
+#  include <inttypes.h>
+#  define FMTd32 PRId32
+#  define FMTu32 PRIu32
+#  define FMTx32 PRIx32
+#  define FMTd64 PRId64
+#  define FMTu64 PRIu64
+#  define FMTx64 PRIx64
+#  define FMTdPTR PRIdPTR
+#  define FMTuPTR PRIuPTR
+#  define FMTxPTR PRIxPTR
+#endif
+
+/* Size of stack-allocated buffer passed to buferror(). */
+#define BUFERROR_BUF		64
+
+/*
+ * Size of stack-allocated buffer used by malloc_{,v,vc}printf().  This must be
+ * large enough for all possible uses within jemalloc.
+ */
+#define MALLOC_PRINTF_BUFSIZE	4096
+
+
+int buferror(int err, char *buf, size_t buflen);
+uintmax_t malloc_strtoumax(const char *restrict nptr, char **restrict endptr,
+    int base);
+void malloc_write(const char *s);
+
+/*
+ * malloc_vsnprintf() supports a subset of snprintf(3) that avoids floating
+ * point math.
+ */
+size_t malloc_vsnprintf(char *str, size_t size, const char *format,
+    va_list ap);
+size_t malloc_snprintf(char *str, size_t size, const char *format, ...)
+    JEMALLOC_FORMAT_PRINTF(3, 4);
+void malloc_vcprintf(void (*write_cb)(void *, const char *), void *cbopaque,
+    const char *format, va_list ap);
+void malloc_cprintf(void (*write)(void *, const char *), void *cbopaque,
+    const char *format, ...) JEMALLOC_FORMAT_PRINTF(3, 4);
+void malloc_printf(const char *format, ...) JEMALLOC_FORMAT_PRINTF(1, 2);
+
+#endif /* JEMALLOC_INTERNAL_MALLOC_IO_H */
diff --git a/include/jemalloc/internal/util.h b/include/jemalloc/internal/util.h
new file mode 100644
index 00000000..88662e89
--- /dev/null
+++ b/include/jemalloc/internal/util.h
@@ -0,0 +1,71 @@
+#ifndef JEMALLOC_INTERNAL_UTIL_H
+#define JEMALLOC_INTERNAL_UTIL_H
+
+#define UTIL_INLINE static inline
+
+/* Junk fill patterns. */
+#ifndef JEMALLOC_ALLOC_JUNK
+#  define JEMALLOC_ALLOC_JUNK	((uint8_t)0xa5)
+#endif
+#ifndef JEMALLOC_FREE_JUNK
+#  define JEMALLOC_FREE_JUNK	((uint8_t)0x5a)
+#endif
+
+/*
+ * Wrap a cpp argument that contains commas such that it isn't broken up into
+ * multiple arguments.
+ */
+#define JEMALLOC_ARG_CONCAT(...) __VA_ARGS__
+
+/* cpp macro definition stringification. */
+#define STRINGIFY_HELPER(x) #x
+#define STRINGIFY(x) STRINGIFY_HELPER(x)
+
+/*
+ * Silence compiler warnings due to uninitialized values.  This is used
+ * wherever the compiler fails to recognize that the variable is never used
+ * uninitialized.
+ */
+#ifdef JEMALLOC_CC_SILENCE
+#  define JEMALLOC_CC_SILENCE_INIT(v) = v
+#else
+#  define JEMALLOC_CC_SILENCE_INIT(v)
+#endif
+
+#ifdef __GNUC__
+#  define likely(x)   __builtin_expect(!!(x), 1)
+#  define unlikely(x) __builtin_expect(!!(x), 0)
+#else
+#  define likely(x)   !!(x)
+#  define unlikely(x) !!(x)
+#endif
+
+#if !defined(JEMALLOC_INTERNAL_UNREACHABLE)
+#  error JEMALLOC_INTERNAL_UNREACHABLE should have been defined by configure
+#endif
+
+#define unreachable() JEMALLOC_INTERNAL_UNREACHABLE()
+
+/* Set error code. */
+UTIL_INLINE void
+set_errno(int errnum) {
+#ifdef _WIN32
+	SetLastError(errnum);
+#else
+	errno = errnum;
+#endif
+}
+
+/* Get last error code. */
+UTIL_INLINE int
+get_errno(void) {
+#ifdef _WIN32
+	return GetLastError();
+#else
+	return errno;
+#endif
+}
+
+#undef UTIL_INLINE
+
+#endif /* JEMALLOC_INTERNAL_UTIL_H */
diff --git a/include/jemalloc/internal/util_externs.h b/include/jemalloc/internal/util_externs.h
deleted file mode 100644
index b203b773..00000000
--- a/include/jemalloc/internal/util_externs.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#ifndef JEMALLOC_INTERNAL_UTIL_EXTERNS_H
-#define JEMALLOC_INTERNAL_UTIL_EXTERNS_H
-
-int	buferror(int err, char *buf, size_t buflen);
-uintmax_t	malloc_strtoumax(const char *restrict nptr,
-    char **restrict endptr, int base);
-void	malloc_write(const char *s);
-
-/*
- * malloc_vsnprintf() supports a subset of snprintf(3) that avoids floating
- * point math.
- */
-size_t	malloc_vsnprintf(char *str, size_t size, const char *format,
-    va_list ap);
-size_t	malloc_snprintf(char *str, size_t size, const char *format, ...)
-    JEMALLOC_FORMAT_PRINTF(3, 4);
-void	malloc_vcprintf(void (*write_cb)(void *, const char *), void *cbopaque,
-    const char *format, va_list ap);
-void malloc_cprintf(void (*write)(void *, const char *), void *cbopaque,
-    const char *format, ...) JEMALLOC_FORMAT_PRINTF(3, 4);
-void	malloc_printf(const char *format, ...) JEMALLOC_FORMAT_PRINTF(1, 2);
-
-#endif /* JEMALLOC_INTERNAL_UTIL_EXTERNS_H */
diff --git a/include/jemalloc/internal/util_types.h b/include/jemalloc/internal/util_types.h
deleted file mode 100644
index e0f79aad..00000000
--- a/include/jemalloc/internal/util_types.h
+++ /dev/null
@@ -1,95 +0,0 @@
-#ifndef JEMALLOC_INTERNAL_UTIL_TYPES_H
-#define JEMALLOC_INTERNAL_UTIL_TYPES_H
-
-#ifdef _WIN32
-#  ifdef _WIN64
-#    define FMT64_PREFIX "ll"
-#    define FMTPTR_PREFIX "ll"
-#  else
-#    define FMT64_PREFIX "ll"
-#    define FMTPTR_PREFIX ""
-#  endif
-#  define FMTd32 "d"
-#  define FMTu32 "u"
-#  define FMTx32 "x"
-#  define FMTd64 FMT64_PREFIX "d"
-#  define FMTu64 FMT64_PREFIX "u"
-#  define FMTx64 FMT64_PREFIX "x"
-#  define FMTdPTR FMTPTR_PREFIX "d"
-#  define FMTuPTR FMTPTR_PREFIX "u"
-#  define FMTxPTR FMTPTR_PREFIX "x"
-#else
-#  include <inttypes.h>
-#  define FMTd32 PRId32
-#  define FMTu32 PRIu32
-#  define FMTx32 PRIx32
-#  define FMTd64 PRId64
-#  define FMTu64 PRIu64
-#  define FMTx64 PRIx64
-#  define FMTdPTR PRIdPTR
-#  define FMTuPTR PRIuPTR
-#  define FMTxPTR PRIxPTR
-#endif
-
-/* Size of stack-allocated buffer passed to buferror(). */
-#define BUFERROR_BUF		64
-
-/*
- * Size of stack-allocated buffer used by malloc_{,v,vc}printf().  This must be
- * large enough for all possible uses within jemalloc.
- */
-#define MALLOC_PRINTF_BUFSIZE	4096
-
-/* Junk fill patterns. */
-#ifndef JEMALLOC_ALLOC_JUNK
-#  define JEMALLOC_ALLOC_JUNK	((uint8_t)0xa5)
-#endif
-#ifndef JEMALLOC_FREE_JUNK
-#  define JEMALLOC_FREE_JUNK	((uint8_t)0x5a)
-#endif
-
-/*
- * Wrap a cpp argument that contains commas such that it isn't broken up into
- * multiple arguments.
- */
-#define JEMALLOC_ARG_CONCAT(...) __VA_ARGS__
-
-/* cpp macro definition stringification. */
-#define STRINGIFY_HELPER(x) #x
-#define STRINGIFY(x) STRINGIFY_HELPER(x)
-
-/*
- * Silence compiler warnings due to uninitialized values.  This is used
- * wherever the compiler fails to recognize that the variable is never used
- * uninitialized.
- */
-#ifdef JEMALLOC_CC_SILENCE
-#  define JEMALLOC_CC_SILENCE_INIT(v) = v
-#else
-#  define JEMALLOC_CC_SILENCE_INIT(v)
-#endif
-
-#ifdef __GNUC__
-#  define likely(x)   __builtin_expect(!!(x), 1)
-#  define unlikely(x) __builtin_expect(!!(x), 0)
-#else
-#  define likely(x)   !!(x)
-#  define unlikely(x) !!(x)
-#endif
-
-#if !defined(JEMALLOC_INTERNAL_UNREACHABLE)
-#  error JEMALLOC_INTERNAL_UNREACHABLE should have been defined by configure
-#endif
-
-#define unreachable() JEMALLOC_INTERNAL_UNREACHABLE()
-
-#include "jemalloc/internal/assert.h"
-
-/* Use to assert a particular configuration, e.g., cassert(config_debug). */
-#define cassert(c) do {							\
-	if (unlikely(!(c))) {						\
-		not_reached();						\
-	}								\
-} while (0)
-
-#endif /* JEMALLOC_INTERNAL_UTIL_TYPES_H */
diff --git a/src/util.c b/src/malloc_io.c
similarity index 94%
rename from src/util.c
rename to src/malloc_io.c
index ee5fa47e..fd6ff0f0 100644
--- a/src/util.c
+++ b/src/malloc_io.c
@@ -1,3 +1,19 @@
+#define JEMALLOC_MALLOC_IO_C_
+#include "jemalloc/internal/jemalloc_internal.h"
+
+#ifdef assert
+#  undef assert
+#endif
+#ifdef not_reached
+#  undef not_reached
+#endif
+#ifdef not_implemented
+#  undef not_implemented
+#endif
+#ifdef assert_not_implemented
+#  undef assert_not_implemented
+#endif
+
 /*
  * Define simple versions of assertion macros that won't recurse in case
  * of assertion failures in malloc_*printf().
@@ -24,22 +40,25 @@
 	}								\
 } while (0)
 
-#define JEMALLOC_UTIL_C_
-#include "jemalloc/internal/jemalloc_internal.h"
+#define assert_not_implemented(e) do {					\
+	if (unlikely(config_debug && !(e))) {				\
+		not_implemented();					\
+	}								\
+} while (0)
 
 /******************************************************************************/
 /* Function prototypes for non-inline static functions. */
 
-static void	wrtmessage(void *cbopaque, const char *s);
-#define U2S_BUFSIZE	((1U << (LG_SIZEOF_INTMAX_T + 3)) + 1)
-static char	*u2s(uintmax_t x, unsigned base, bool uppercase, char *s,
+static void wrtmessage(void *cbopaque, const char *s);
+#define U2S_BUFSIZE ((1U << (LG_SIZEOF_INTMAX_T + 3)) + 1)
+static char *u2s(uintmax_t x, unsigned base, bool uppercase, char *s,
     size_t *slen_p);
-#define D2S_BUFSIZE	(1 + U2S_BUFSIZE)
-static char	*d2s(intmax_t x, char sign, char *s, size_t *slen_p);
-#define O2S_BUFSIZE	(1 + U2S_BUFSIZE)
-static char	*o2s(uintmax_t x, bool alt_form, char *s, size_t *slen_p);
-#define X2S_BUFSIZE	(2 + U2S_BUFSIZE)
-static char	*x2s(uintmax_t x, bool alt_form, bool uppercase, char *s,
+#define D2S_BUFSIZE (1 + U2S_BUFSIZE)
+static char *d2s(intmax_t x, char sign, char *s, size_t *slen_p);
+#define O2S_BUFSIZE (1 + U2S_BUFSIZE)
+static char *o2s(uintmax_t x, bool alt_form, char *s, size_t *slen_p);
+#define X2S_BUFSIZE (2 + U2S_BUFSIZE)
+static char *x2s(uintmax_t x, bool alt_form, bool uppercase, char *s,
     size_t *slen_p);
 
 /******************************************************************************/
@@ -662,4 +681,5 @@ malloc_printf(const char *format, ...) {
 #undef assert
 #undef not_reached
 #undef not_implemented
+#undef assert_not_implemented
 #include "jemalloc/internal/assert.h"
diff --git a/test/include/test/jemalloc_test.h.in b/test/include/test/jemalloc_test.h.in
index 36d59cff..0770d020 100644
--- a/test/include/test/jemalloc_test.h.in
+++ b/test/include/test/jemalloc_test.h.in
@@ -69,12 +69,15 @@ static const bool config_debug =
 #  define JEMALLOC_N(n) @private_namespace@##n
 #  include "jemalloc/internal/private_namespace.h"
 
+/* Hermetic headers. */
+#  include "jemalloc/internal/assert.h"
+#  include "jemalloc/internal/malloc_io.h"
+#  include "jemalloc/internal/util.h"
+
+/* Non-hermetic headers. */
 #  include "jemalloc/internal/nstime_types.h"
 #  include "jemalloc/internal/nstime_structs.h"
 #  include "jemalloc/internal/nstime_externs.h"
-#  include "jemalloc/internal/util_types.h"
-#  include "jemalloc/internal/util_externs.h"
-#  include "jemalloc/internal/util_inlines.h"
 #  include "jemalloc/internal/qr.h"
 #  include "jemalloc/internal/ql.h"
 
diff --git a/test/unit/bit_util.c b/test/unit/bit_util.c
new file mode 100644
index 00000000..fe5c4473
--- /dev/null
+++ b/test/unit/bit_util.c
@@ -0,0 +1,55 @@
+#include "test/jemalloc_test.h"
+
+#define TEST_POW2_CEIL(t, suf, pri) do {				\
+	unsigned i, pow2;						\
+	t x;								\
+									\
+	assert_##suf##_eq(pow2_ceil_##suf(0), 0, "Unexpected result");	\
+									\
+	for (i = 0; i < sizeof(t) * 8; i++) {				\
+		assert_##suf##_eq(pow2_ceil_##suf(((t)1) << i), ((t)1)	\
+		    << i, "Unexpected result");				\
+	}								\
+									\
+	for (i = 2; i < sizeof(t) * 8; i++) {				\
+		assert_##suf##_eq(pow2_ceil_##suf((((t)1) << i) - 1),	\
+		    ((t)1) << i, "Unexpected result");			\
+	}								\
+									\
+	for (i = 0; i < sizeof(t) * 8 - 1; i++) {			\
+		assert_##suf##_eq(pow2_ceil_##suf((((t)1) << i) + 1),	\
+		    ((t)1) << (i+1), "Unexpected result");		\
+	}								\
+									\
+	for (pow2 = 1; pow2 < 25; pow2++) {				\
+		for (x = (((t)1) << (pow2-1)) + 1; x <= ((t)1) << pow2;	\
+		    x++) {						\
+			assert_##suf##_eq(pow2_ceil_##suf(x),		\
+			    ((t)1) << pow2,				\
+			    "Unexpected result, x=%"pri, x);		\
+		}							\
+	}								\
+} while (0)
+
+TEST_BEGIN(test_pow2_ceil_u64) {
+	TEST_POW2_CEIL(uint64_t, u64, FMTu64);
+}
+TEST_END
+
+TEST_BEGIN(test_pow2_ceil_u32) {
+	TEST_POW2_CEIL(uint32_t, u32, FMTu32);
+}
+TEST_END
+
+TEST_BEGIN(test_pow2_ceil_zu) {
+	TEST_POW2_CEIL(size_t, zu, "zu");
+}
+TEST_END
+
+int
+main(void) {
+	return test(
+	    test_pow2_ceil_u64,
+	    test_pow2_ceil_u32,
+	    test_pow2_ceil_zu);
+}
diff --git a/test/unit/util.c b/test/unit/malloc_io.c
similarity index 86%
rename from test/unit/util.c
rename to test/unit/malloc_io.c
index 5760966f..79ba7fc5 100644
--- a/test/unit/util.c
+++ b/test/unit/malloc_io.c
@@ -1,51 +1,5 @@
 #include "test/jemalloc_test.h"
 
-#define TEST_POW2_CEIL(t, suf, pri) do {				\
-	unsigned i, pow2;						\
-	t x;								\
-									\
-	assert_##suf##_eq(pow2_ceil_##suf(0), 0, "Unexpected result");	\
-									\
-	for (i = 0; i < sizeof(t) * 8; i++) {				\
-		assert_##suf##_eq(pow2_ceil_##suf(((t)1) << i), ((t)1)	\
-		    << i, "Unexpected result");				\
-	}								\
-									\
-	for (i = 2; i < sizeof(t) * 8; i++) {				\
-		assert_##suf##_eq(pow2_ceil_##suf((((t)1) << i) - 1),	\
-		    ((t)1) << i, "Unexpected result");			\
-	}								\
-									\
-	for (i = 0; i < sizeof(t) * 8 - 1; i++) {			\
-		assert_##suf##_eq(pow2_ceil_##suf((((t)1) << i) + 1),	\
-		    ((t)1) << (i+1), "Unexpected result");		\
-	}								\
-									\
-	for (pow2 = 1; pow2 < 25; pow2++) {				\
-		for (x = (((t)1) << (pow2-1)) + 1; x <= ((t)1) << pow2;	\
-		    x++) {						\
-			assert_##suf##_eq(pow2_ceil_##suf(x),		\
-			    ((t)1) << pow2,				\
-			    "Unexpected result, x=%"pri, x);		\
-		}							\
-	}								\
-} while (0)
-
-TEST_BEGIN(test_pow2_ceil_u64) {
-	TEST_POW2_CEIL(uint64_t, u64, FMTu64);
-}
-TEST_END
-
-TEST_BEGIN(test_pow2_ceil_u32) {
-	TEST_POW2_CEIL(uint32_t, u32, FMTu32);
-}
-TEST_END
-
-TEST_BEGIN(test_pow2_ceil_zu) {
-	TEST_POW2_CEIL(size_t, zu, "zu");
-}
-TEST_END
-
 TEST_BEGIN(test_malloc_strtoumax_no_endptr) {
 	int err;
 
@@ -297,9 +251,6 @@ TEST_END
 int
 main(void) {
 	return test(
-	    test_pow2_ceil_u64,
-	    test_pow2_ceil_u32,
-	    test_pow2_ceil_zu,
 	    test_malloc_strtoumax_no_endptr,
 	    test_malloc_strtoumax,
 	    test_malloc_snprintf_truncated,