diff --git a/Makefile.in b/Makefile.in
index 82939be3..8e55e83e 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -96,7 +96,7 @@ LIBOBJ = stdlib/snprintf.$(O) stdlib/vsnprintf.$(O) stdlib/strlcpy.$(O) \
 	stdlib/strnlen.$(O) stdlib/strrchrnul.$(O) \
 	\
 	nasmlib/ver.$(O) \
-	nasmlib/crc64.$(O) nasmlib/malloc.$(O) \
+	nasmlib/crc64.$(O) nasmlib/alloc.$(O) nasmlib/asprintf.$(O) \
 	nasmlib/md5c.$(O) nasmlib/string.$(O) nasmlib/nctype.$(O) \
 	nasmlib/file.$(O) nasmlib/mmap.$(O) nasmlib/ilog2.$(O) \
 	nasmlib/realpath.$(O) nasmlib/path.$(O) \
diff --git a/Mkfiles/msvc.mak b/Mkfiles/msvc.mak
index 7ea3b55a..89e392d9 100644
--- a/Mkfiles/msvc.mak
+++ b/Mkfiles/msvc.mak
@@ -68,11 +68,11 @@ LIBOBJ = stdlib\snprintf.$(O) stdlib\vsnprintf.$(O) stdlib\strlcpy.$(O) \
 	stdlib\strnlen.$(O) stdlib\strrchrnul.$(O) \
 	\
 	nasmlib\ver.$(O) \
-	nasmlib\crc64.$(O) nasmlib\malloc.$(O) \
+	nasmlib\crc64.$(O) nasmlib\alloc.$(O) nasmlib\asprintf.$(O) \
 	nasmlib\md5c.$(O) nasmlib\string.$(O) nasmlib\nctype.$(O) \
 	nasmlib\file.$(O) nasmlib\mmap.$(O) nasmlib\ilog2.$(O) \
 	nasmlib\realpath.$(O) nasmlib\path.$(O) \
-	nasmlib\filename.$(O) nasmlib\srcfile.$(O) \
+	nasmlib\filename.$(O) \
 	nasmlib\zerobuf.$(O) nasmlib\readnum.$(O) nasmlib\bsi.$(O) \
 	nasmlib\rbtree.$(O) nasmlib\hashtbl.$(O) \
 	nasmlib\raa.$(O) nasmlib\saa.$(O) \
@@ -97,7 +97,7 @@ LIBOBJ = stdlib\snprintf.$(O) stdlib\vsnprintf.$(O) stdlib\strlcpy.$(O) \
 	asm\segalloc.$(O) \
 	asm\preproc-nop.$(O) \
 	asm\rdstrnum.$(O) \
-	\
+	asm\srcfile.$(O) \
 	macros\macros.$(O) \
 	\
 	output\outform.$(O) output\outlib.$(O) output\legacy.$(O) \
diff --git a/Mkfiles/openwcom.mak b/Mkfiles/openwcom.mak
index 2b0031af..1c407dea 100644
--- a/Mkfiles/openwcom.mak
+++ b/Mkfiles/openwcom.mak
@@ -57,11 +57,11 @@ LIBOBJ = stdlib\snprintf.$(O) stdlib\vsnprintf.$(O) stdlib\strlcpy.$(O) &
 	stdlib\strnlen.$(O) stdlib\strrchrnul.$(O) &
 	&
 	nasmlib\ver.$(O) &
-	nasmlib\crc64.$(O) nasmlib\malloc.$(O) &
+	nasmlib\crc64.$(O) nasmlib\alloc.$(O) nasmlib\asprintf.$(O) &
 	nasmlib\md5c.$(O) nasmlib\string.$(O) nasmlib\nctype.$(O) &
 	nasmlib\file.$(O) nasmlib\mmap.$(O) nasmlib\ilog2.$(O) &
 	nasmlib\realpath.$(O) nasmlib\path.$(O) &
-	nasmlib\filename.$(O) nasmlib\srcfile.$(O) &
+	nasmlib\filename.$(O) &
 	nasmlib\zerobuf.$(O) nasmlib\readnum.$(O) nasmlib\bsi.$(O) &
 	nasmlib\rbtree.$(O) nasmlib\hashtbl.$(O) &
 	nasmlib\raa.$(O) nasmlib\saa.$(O) &
@@ -86,7 +86,7 @@ LIBOBJ = stdlib\snprintf.$(O) stdlib\vsnprintf.$(O) stdlib\strlcpy.$(O) &
 	asm\segalloc.$(O) &
 	asm\preproc-nop.$(O) &
 	asm\rdstrnum.$(O) &
-	&
+	asm\srcfile.$(O) &
 	macros\macros.$(O) &
 	&
 	output\outform.$(O) output\outlib.$(O) output\legacy.$(O) &
diff --git a/configure.ac b/configure.ac
index 2b2858ec..878b3269 100644
--- a/configure.ac
+++ b/configure.ac
@@ -118,6 +118,8 @@ AC_CHECK_FUNCS(strrchrnul)
 AC_CHECK_FUNCS(iscntrl)
 AC_CHECK_FUNCS(isascii)
 
+AC_CHECK_FUNCS(vasprintf)
+
 AC_CHECK_FUNCS(getuid)
 AC_CHECK_FUNCS(getgid)
 
diff --git a/include/compiler.h b/include/compiler.h
index 4178c98e..4ce60ccc 100644
--- a/include/compiler.h
+++ b/include/compiler.h
@@ -1,6 +1,6 @@
 /* ----------------------------------------------------------------------- *
  *   
- *   Copyright 2007-2017 The NASM Authors - All Rights Reserved
+ *   Copyright 2007-2018 The NASM Authors - All Rights Reserved
  *   See the file AUTHORS included with the NASM distribution for
  *   the specific copyright holders.
  *
@@ -81,6 +81,7 @@
 #include <stddef.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <limits.h>
 
 #ifdef HAVE_SYS_TYPES_H
@@ -350,6 +351,24 @@ size_t strnlen(const char *s, size_t maxlen);
 # define is_constant(x) false
 #endif
 
+/*
+ * The autoconf documentation states:
+ *
+ * `va_copy'
+ *    The C99 standard provides `va_copy' for copying `va_list'
+ *    variables.  It may be available in older environments too, though
+ *    possibly as `__va_copy' (e.g., `gcc' in strict pre-C99 mode).
+ *    These can be tested with `#ifdef'.  A fallback to `memcpy (&dst,
+ *    &src, sizeof (va_list))' gives maximum portability.
+ */
+#ifndef va_copy
+# ifdef __va_copy
+#  define va_copy(dst,src) __va_copy(dst,src)
+# else
+#  define va_copy(dst,src) memcpy(&(dst),&(src),sizeof(va_list))
+# endif
+#endif
+
 /* Watcom doesn't handle switch statements with 64-bit types, hack around it */
 #ifdef __WATCOMC__
 # define BOGUS_CASE 0x76543210
diff --git a/include/nasmlib.h b/include/nasmlib.h
index db624987..7d07a216 100644
--- a/include/nasmlib.h
+++ b/include/nasmlib.h
@@ -48,11 +48,11 @@
 #endif
 
 /*
- * Wrappers around malloc, realloc and free. nasm_malloc will
- * fatal-error and die rather than return NULL; nasm_realloc will
- * do likewise, and will also guarantee to work right on being
- * passed a NULL pointer; nasm_free will do nothing if it is passed
- * a NULL pointer.
+ * Wrappers around malloc, realloc, free and a few more. nasm_malloc
+ * will fatal-error and die rather than return NULL; nasm_realloc will
+ * do likewise, and will also guarantee to work right on being passed
+ * a NULL pointer; nasm_free will do nothing if it is passed a NULL
+ * pointer.
  */
 void * safe_malloc(1) nasm_malloc(size_t);
 void * safe_malloc(1) nasm_zalloc(size_t);
@@ -64,6 +64,14 @@ char * safe_alloc nasm_strndup(const char *, size_t);
 char * safe_alloc nasm_strcat(const char *one, const char *two);
 char * safe_alloc end_with_null nasm_strcatn(const char *one, ...);
 
+/*
+ * Variants on asprintf(). Note that unlike the standard version, we
+ * return the pointer rather than the length; if you want the length
+ * use %n.
+ */
+char * safe_alloc nasm_asprintf(const char *fmt, ...);
+char * safe_alloc nasm_vasprintf(const char *fmt, va_list ap);
+
 /* Assert the argument is a pointer without evaluating it */
 #define nasm_assert_pointer(p) ((void)sizeof(*(p)))
 
diff --git a/nasmlib/malloc.c b/nasmlib/alloc.c
similarity index 95%
rename from nasmlib/malloc.c
rename to nasmlib/alloc.c
index 1e643185..2f3f9519 100644
--- a/nasmlib/malloc.c
+++ b/nasmlib/alloc.c
@@ -36,24 +36,15 @@
  */
 
 #include "compiler.h"
-
-#include <stdlib.h>
-
 #include "nasmlib.h"
 #include "error.h"
+#include "alloc.h"
 
-static no_return nasm_alloc_failed(void)
+no_return nasm_alloc_failed(void)
 {
     nasm_fatal("out of memory");
 }
 
-static inline void *validate_ptr(void *p)
-{
-    if (unlikely(!p))
-        nasm_alloc_failed();
-    return p;
-}
-
 void *nasm_malloc(size_t size)
 {
     return validate_ptr(malloc(size));
diff --git a/nasmlib/alloc.h b/nasmlib/alloc.h
new file mode 100644
index 00000000..c599d213
--- /dev/null
+++ b/nasmlib/alloc.h
@@ -0,0 +1,48 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 1996-2018 The NASM Authors - All Rights Reserved
+ *   See the file AUTHORS included with the NASM distribution for
+ *   the specific copyright holders.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following
+ *   conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ *     copyright notice, this list of conditions and the following
+ *     disclaimer in the documentation and/or other materials provided
+ *     with the distribution.
+ *
+ *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * ----------------------------------------------------------------------- */
+
+#ifndef NASMLIB_ALLOC_H
+#define NASMLIB_ALLOC_H
+
+#include "compiler.h"
+
+no_return nasm_alloc_failed(void);
+
+static inline void *validate_ptr(void *p)
+{
+    if (unlikely(!p))
+        nasm_alloc_failed();
+    return p;
+}
+
+#endif /* NASMLIB_ALLOC_H */