diff --git a/sds.h b/sds.h
index 26f84e3..b53f24d 100644
--- a/sds.h
+++ b/sds.h
@@ -45,12 +45,12 @@ struct sdshdr {
 };
 
 static inline size_t sdslen(const sds s) {
-    struct sdshdr *sh = (void*)(s-sizeof *sh);
+    struct sdshdr *sh = (struct sdshdr *)(s-sizeof *sh);
     return sh->len;
 }
 
 static inline size_t sdsavail(const sds s) {
-    struct sdshdr *sh = (void*)(s-sizeof *sh);
+    struct sdshdr *sh = (struct sdshdr *)(s-sizeof *sh);
     return sh->free;
 }