diff --git a/src/core/malloc.c b/src/core/malloc.c
index bb34db31..db2b500c 100644
--- a/src/core/malloc.c
+++ b/src/core/malloc.c
@@ -134,8 +134,6 @@ void * alloc_memblock ( size_t size, size_t align ) {
 			 */
 			if ( pre_size < MIN_MEMBLOCK_SIZE )
 				list_del ( &pre->list );
-			/* Zero allocated memory, for calloc() */
-			memset ( block, 0, size );
 			DBG ( "Allocated [%p,%p)\n", block,
 			      ( ( ( void * ) block ) + size ) );
 			return block;
@@ -297,6 +295,23 @@ void free ( void *ptr ) {
 	realloc ( ptr, 0 );
 }
 
+/**
+ * Allocate cleared memory
+ *
+ * @v size		Requested size
+ * @ret ptr		Allocated memory
+ *
+ * Allocate memory as per malloc(), and zero it.
+ */
+void * _calloc ( size_t size ) {
+	void *data;
+
+	data = malloc ( size );
+	if ( data )
+		memset ( data, 0, size );
+	return data;
+}
+
 /**
  * Add memory to allocation pool
  *
diff --git a/src/include/stdlib.h b/src/include/stdlib.h
index 2b6471e1..39ad831f 100644
--- a/src/include/stdlib.h
+++ b/src/include/stdlib.h
@@ -8,6 +8,8 @@ extern void free ( void *ptr );
 extern int system ( const char *command );
 extern long int random ( void );
 
+extern void * _calloc ( size_t len );
+
 /**
  * Allocate cleared memory
  *
@@ -17,12 +19,12 @@ extern long int random ( void );
  *
  * Allocate memory as per malloc(), and zero it.
  *
- * Note that malloc() and calloc() are identical, in the interests of
- * reducing code size.  Callers should not, however, rely on malloc()
- * clearing memory, since this behaviour may change in future.
+ * This is implemented as a static inline, with the body of the
+ * function in _calloc(), since in most cases @c nmemb will be 1 and
+ * doing the multiply is just wasteful.
  */
 static inline void * calloc ( size_t nmemb, size_t size ) {
-	return malloc ( nmemb * size );
+	return _calloc ( nmemb * size );
 }
 
 #endif /* STDLIB_H */