diff --git a/configure.ac.tpl b/configure.ac.tpl
index bb5e04a..de3995c 100644
--- a/configure.ac.tpl
+++ b/configure.ac.tpl
@@ -72,6 +72,11 @@ AC_CHECK_FUNC(strndup,
 	AC_DEFINE(NO_STRNDUP)
 	AM_CONDITIONAL(NO_STRNDUP, true))
 
+AC_CHECK_FUNC(asprintf,
+	AM_CONDITIONAL(NO_ASPRINTF, false),
+	AC_DEFINE(NO_ASPRINTF)
+	AM_CONDITIONAL(NO_ASPRINTF, true))
+
 AC_CHECK_FUNC(reallocarray,
 	AM_CONDITIONAL(NO_REALLOCARRAY, false),
 	AC_DEFINE(NO_REALLOCARRAY)
diff --git a/crypto/Makefile.am.tpl b/crypto/Makefile.am.tpl
index 6ac6c4f..7688fb9 100644
--- a/crypto/Makefile.am.tpl
+++ b/crypto/Makefile.am.tpl
@@ -38,6 +38,10 @@ libcompat_la_SOURCES += compat/strndup.c
 libcompat_la_SOURCES += compat/strnlen.c
 endif
 
+if NO_ASPRINTF
+libcompat_la_SOURCES += compat/asprintf.c
+endif
+
 if NO_REALLOCARRAY
 libcompat_la_SOURCES += compat/reallocarray.c
 endif
diff --git a/crypto/compat/asprintf.c b/crypto/compat/asprintf.c
new file mode 100644
index 0000000..45a539d
--- /dev/null
+++ b/crypto/compat/asprintf.c
@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2004 Darren Tucker.
+ *
+ * Based originally on asprintf.c from OpenBSD:
+ * Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdlib.h>
+
+#ifndef VA_COPY
+# ifdef HAVE_VA_COPY
+#  define VA_COPY(dest, src) va_copy(dest, src)
+# else
+#  ifdef HAVE___VA_COPY
+#   define VA_COPY(dest, src) __va_copy(dest, src)
+#  else
+#   define VA_COPY(dest, src) (dest) = (src)
+#  endif
+# endif
+#endif
+
+#define INIT_SZ	128
+
+int
+vasprintf(char **str, const char *fmt, va_list ap)
+{
+	int ret = -1;
+	va_list ap2;
+	char *string, *newstr;
+	size_t len;
+
+	VA_COPY(ap2, ap);
+	if ((string = malloc(INIT_SZ)) == NULL)
+		goto fail;
+
+	ret = vsnprintf(string, INIT_SZ, fmt, ap2);
+	if (ret >= 0 && ret < INIT_SZ) { /* succeeded with initial alloc */
+		*str = string;
+	} else if (ret == INT_MAX || ret < 0) { /* Bad length */
+		free(string);
+		goto fail;
+	} else {	/* bigger than initial, realloc allowing for nul */
+		len = (size_t)ret + 1;
+		if ((newstr = realloc(string, len)) == NULL) {
+			free(string);
+			goto fail;
+		} else {
+			va_end(ap2);
+			VA_COPY(ap2, ap);
+			ret = vsnprintf(newstr, len, fmt, ap2);
+			if (ret >= 0 && (size_t)ret < len) {
+				*str = newstr;
+			} else { /* failed with realloc'ed string, give up */
+				free(newstr);
+				goto fail;
+			}
+		}
+	}
+	va_end(ap2);
+	return (ret);
+
+fail:
+	*str = NULL;
+	errno = ENOMEM;
+	va_end(ap2);
+	return (-1);
+}
+
+int asprintf(char **str, const char *fmt, ...)
+{
+	va_list ap;
+	int ret;
+	
+	*str = NULL;
+	va_start(ap, fmt);
+	ret = vasprintf(str, fmt, ap);
+	va_end(ap);
+
+	return ret;
+}
diff --git a/include/Makefile.am b/include/Makefile.am
index 889f775..d4487d7 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -2,6 +2,7 @@ SUBDIRS = openssl
 
 noinst_HEADERS = err.h
 noinst_HEADERS += pqueue.h
+noinst_HEADERS += stdio.h
 noinst_HEADERS += stdlib.h
 noinst_HEADERS += string.h
 noinst_HEADERS += unistd.h
diff --git a/include/stdio.h b/include/stdio.h
new file mode 100644
index 0000000..e23fbe5
--- /dev/null
+++ b/include/stdio.h
@@ -0,0 +1,11 @@
+#include_next <stdio.h>
+
+#ifndef LIBCRYPTOCOMPAT_STDIO_H
+#define LIBCRYPTOCOMPAT_STDIO_H
+
+#ifdef NO_ASPRINTF
+int vasprintf(char **str, const char *fmt, va_list ap);
+int asprintf(char **str, const char *fmt, ...);
+#endif
+
+#endif