diff --git a/lib/roken/parse_reply-test.c b/lib/roken/parse_reply-test.c
index aabfdc493..e7e59bf23 100644
--- a/lib/roken/parse_reply-test.c
+++ b/lib/roken/parse_reply-test.c
@@ -109,18 +109,18 @@ main(int argc, char **argv)
 #endif
 	flags |= MAP_PRIVATE;
 
-	p1 = (char *)mmap(0, 2 * pagesize, PROT_READ | PROT_WRITE,
+	p1 = (unsigned char *)mmap(0, 2 * pagesize, PROT_READ | PROT_WRITE,
 		  flags, fd, 0);
 	if (p1 == (unsigned char *)MAP_FAILED)
 	    err (1, "mmap");
 	p2 = p1 + pagesize;
-	ret = mprotect (p2, pagesize, 0);
+	ret = mprotect ((void *)p2, pagesize, 0);
 	if (ret < 0)
 	    err (1, "mprotect");
 	buf = p2 - t->buf_len;
 	memcpy (buf, t->buf, t->buf_len);
 	parse_reply (buf, t->buf_len);
-	ret = munmap (p1, 2 * pagesize);
+	ret = munmap ((void *)p1, 2 * pagesize);
 	if (ret < 0)
 	    err (1, "munmap");
     }
diff --git a/lib/roken/test-mem.c b/lib/roken/test-mem.c
index e3cebe7d7..42bfe7c57 100644
--- a/lib/roken/test-mem.c
+++ b/lib/roken/test-mem.c
@@ -126,14 +126,14 @@ rk_test_mem_alloc(enum rk_test_mem_type type, const char *name,
 
     map.size = size + pagesize - (size % pagesize) + pagesize * 2;
 
-    p = (char *)mmap(0, map.size, PROT_READ | PROT_WRITE,
-		     flags, fd, 0);
+    p = (unsigned char *)mmap(0, map.size, PROT_READ | PROT_WRITE,
+			      flags, fd, 0);
     if (p == (unsigned char *)MAP_FAILED)
 	err (1, "mmap");
 
     map.start = p;
 
-    ret = mprotect (p, pagesize, 0);
+    ret = mprotect ((void *)p, pagesize, 0);
     if (ret < 0)
 	err (1, "mprotect");