diff --git a/mps/code/check.h b/mps/code/check.h
index 9d57678d9ea..eb7219bbe05 100644
--- a/mps/code/check.h
+++ b/mps/code/check.h
@@ -1,7 +1,7 @@
 /* check.h: ASSERTION INTERFACE
  *
  * $Id$
- * Copyright (c) 2001-2016 Ravenbrook Limited.  See end of file for license.
+ * Copyright (c) 2001-2017 Ravenbrook Limited.  See end of file for license.
  * Portions copyright (C) 2002 Global Graphics Software.
  *
  * .aver: This header defines a family of AVER and NOTREACHED macros.
@@ -56,9 +56,10 @@
       mps_lib_assert_fail(MPS_FILE, __LINE__, (condstring)); \
   END
 
-#define ASSERTP(cond, condstring, dflt) \
-  (LIKELY(cond) ? (dflt) : \
-   mps_lib_assert_fail_expr(MPS_FILE, __LINE__, condstring, dflt))
+#define ASSERTP(cond, condstring, default_) \
+  ((void)(LIKELY(cond) \
+          || (mps_lib_assert_fail(MPS_FILE, __LINE__, (condstring)), FALSE)), \
+   (default_))
 
 #define ASSERT_ISTYPE(type, val) (type ## Check(val))
 #define ASSERT_TYPECHECK(type, val) \
@@ -373,7 +374,7 @@ extern unsigned CheckLevel;
 
 /* C. COPYRIGHT AND LICENSE
  *
- * Copyright (C) 2001-2016 Ravenbrook Limited <http://www.ravenbrook.com/>.
+ * Copyright (C) 2001-2017 Ravenbrook Limited <http://www.ravenbrook.com/>.
  * All rights reserved.  This is an open source license.  Contact
  * Ravenbrook for commercial licensing options.
  * 
diff --git a/mps/code/mpslib.h b/mps/code/mpslib.h
index 60db38b2123..e8e2d8dfd95 100644
--- a/mps/code/mpslib.h
+++ b/mps/code/mpslib.h
@@ -1,7 +1,7 @@
 /* mpslib.h: RAVENBROOK MEMORY POOL SYSTEM LIBRARY INTERFACE
  *
  * $Id$
- * Copyright (c) 2001 Ravenbrook Limited.  See end of file for license.
+ * Copyright (c) 2001-2017 Ravenbrook Limited.  See end of file for license.
  *
  * .readership: MPS client application developers, MPS developers.
  * .sources: <design/lib/>
@@ -44,7 +44,6 @@ extern int mps_lib_fputs(const char *, mps_lib_FILE *);
    environment it can return and the MPS will attempt to continue, though
    this may cause failure of the process soon after. */
 extern void mps_lib_assert_fail(const char *, unsigned, const char *);
-extern void *mps_lib_assert_fail_expr(const char *, unsigned, const char *, void *);
 
 /* The default ANSI plinth in mpsliban.c allows the assertion handler to be
    replaced by passing a replacement to `mps_lib_assert_fail_install`,
@@ -79,7 +78,7 @@ extern unsigned long mps_lib_telemetry_control(void);
 
 /* C. COPYRIGHT AND LICENSE
  *
- * Copyright (C) 2001-2002 Ravenbrook Limited <http://www.ravenbrook.com/>.
+ * Copyright (C) 2001-2017 Ravenbrook Limited <http://www.ravenbrook.com/>.
  * All rights reserved.  This is an open source license.  Contact
  * Ravenbrook for commercial licensing options.
  * 
diff --git a/mps/code/mpsliban.c b/mps/code/mpsliban.c
index e18d87ea5e6..4a9c28d7ab3 100644
--- a/mps/code/mpsliban.c
+++ b/mps/code/mpsliban.c
@@ -1,7 +1,7 @@
 /* mpsliban.c: RAVENBROOK MEMORY POOL SYSTEM LIBRARY INTERFACE (ANSI)
  *
  * $Id$
- * Copyright (c) 2001-2014 Ravenbrook Limited.  See end of file for license.
+ * Copyright (c) 2001-2017 Ravenbrook Limited.  See end of file for license.
  * Portions copyright (c) 2002 Global Graphics Software.
  *
  * .purpose: The purpose of this code is
@@ -87,15 +87,6 @@ void mps_lib_assert_fail(const char *file,
   mps_lib_assert_handler(file, line, condition);
 }
 
-extern void *mps_lib_assert_fail_expr(const char *file,
-                                      unsigned line,
-                                      const char *condition,
-                                      void *p)
-{
-  mps_lib_assert_fail(file, line, condition);
-  return p;
-}
-
 mps_lib_assert_fail_t mps_lib_assert_fail_install(mps_lib_assert_fail_t handler)
 {
   mps_lib_assert_fail_t old_handler = mps_lib_assert_handler;
@@ -215,7 +206,7 @@ unsigned long mps_lib_telemetry_control(void)
 
 /* C. COPYRIGHT AND LICENSE
  *
- * Copyright (C) 2001-2014 Ravenbrook Limited <http://www.ravenbrook.com/>.
+ * Copyright (C) 2001-2017 Ravenbrook Limited <http://www.ravenbrook.com/>.
  * All rights reserved.  This is an open source license.  Contact
  * Ravenbrook for commercial licensing options.
  *