diff --git a/Makefile b/Makefile
index bddcc22..14e0c18 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,7 @@ ZIG ?= zig
 PREFIX ?= /usr/local
 BINDIR ?= ${PREFIX}/bin
 MANDIR ?= ${PREFIX}/share/man/man1
-ZIG_FLAGS ?= --release
+ZIG_FLAGS ?= --release=fast
 
 NCDU_VERSION=$(shell grep 'program_version = "' src/main.zig | sed -e 's/^.*"\(.\+\)".*$$/\1/')
 
diff --git a/build.zig b/build.zig
index 231c2e6..73e957b 100644
--- a/build.zig
+++ b/build.zig
@@ -5,9 +5,7 @@ const std = @import("std");
 
 pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
-    const optimize = b.standardOptimizeOption(.{
-        .preferred_optimize_mode = .ReleaseFast,
-    });
+    const optimize = b.standardOptimizeOption(.{});
 
     const pie = b.option(bool, "pie", "Build with PIE support (by default false)") orelse false;