diff --git a/arch/sandbox/cpu/os.c b/arch/sandbox/cpu/os.c
index 725b505..2e2fc58 100644
--- a/arch/sandbox/cpu/os.c
+++ b/arch/sandbox/cpu/os.c
@@ -143,7 +143,7 @@
 	return hdr + 1;
 }
 
-void *os_free(void *ptr)
+void os_free(void *ptr)
 {
 	struct os_mem_hdr *hdr = ptr;