diff --git a/lib/isc/mem.c b/lib/isc/mem.c
index 7a2691f481..120760ee23 100644
--- a/lib/isc/mem.c
+++ b/lib/isc/mem.c
@@ -14,6 +14,7 @@
 #include <config.h>
 
 #include <inttypes.h>
+#include <errno.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -712,10 +713,32 @@ mem_putstats(isc__mem_t *ctx, void *ptr, size_t size) {
 
 static void *
 default_memalloc(void *arg, size_t size) {
+	void *ptr;
 	UNUSED(arg);
-	if (size == 0U)
-		size = 1;
-	return (malloc(size));
+
+	ptr = malloc(size);
+
+	/*
+	 * If the space cannot be allocated, a null pointer is returned. If the
+	 * size of the space requested is zero, the behavior is
+	 * implementation-defined: either a null pointer is returned, or the
+	 * behavior is as if the size were some nonzero value, except that the
+	 * returned pointer shall not be used to access an object.
+	 * [ISO9899 § 7.22.3]
+	 *
+	 * [ISO9899]
+	 *   ISO/IEC WG 9899:2011: Programming languages - C.
+	 *   International Organization for Standardization, Geneva, Switzerland.
+	 *   http://www.open-std.org/JTC1/SC22/WG14/www/docs/n1570.pdf
+	 */
+
+	if (ptr == NULL && size != 0) {
+		char strbuf[ISC_STRERRORSIZE];
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		isc_error_fatal(__FILE__, __LINE__, "malloc failed: %s", strbuf);
+	}
+
+	return (ptr);
 }
 
 static void