diff --git a/README b/README
index 11e9d31285..f704eb3780 100644
--- a/README
+++ b/README
@@ -3749,6 +3749,9 @@ Configuration Settings:
 		The memory will be freed (or in fact just forgotton) when
 		U-Boot relocates itself.
 
+		Pre-relocation malloc() is only supported on sandbox
+		at present but is fairly easy to enable for other archs.
+
 - CONFIG_SYS_BOOTM_LEN:
 		Normally compressed uImages are limited to an
 		uncompressed size of 8 MBytes. If this is not enough,
diff --git a/arch/sandbox/cpu/start.c b/arch/sandbox/cpu/start.c
index 5289291bc8..b3d70515dc 100644
--- a/arch/sandbox/cpu/start.c
+++ b/arch/sandbox/cpu/start.c
@@ -240,6 +240,9 @@ int main(int argc, char *argv[])
 
 	memset(&data, '\0', sizeof(data));
 	gd = &data;
+#ifdef CONFIG_SYS_MALLOC_F_LEN
+	gd->malloc_base = CONFIG_MALLOC_F_ADDR;
+#endif
 
 	/* Do pre- and post-relocation init */
 	board_init_f(0);