diff --git a/src/c/unixfsys.d b/src/c/unixfsys.d
index 610fb3176..8f6f3cb8f 100644
--- a/src/c/unixfsys.d
+++ b/src/c/unixfsys.d
@@ -1123,7 +1123,7 @@ si_chmod(cl_object file, cl_object mode)
 {
 	mode_t code = fixnnint(mode);
 	cl_object filename = si_coerce_to_filename(file);
-	unlikely_if (!chmod((char*)filename->base_string.self, code)) {
+	unlikely_if (chmod((char*)filename->base_string.self, code)) {
 		FElibc_error("Unable to change mode of file~%~S~%to value ~O",
 			     2, file, mode);
 	}