diff --git a/go.mod b/go.mod
index 37ee48af9..f9f4dbfc2 100644
--- a/go.mod
+++ b/go.mod
@@ -27,7 +27,7 @@ require (
 	github.com/cespare/xxhash/v2 v2.3.0
 	github.com/clbanning/mxj/v2 v2.7.0
 	github.com/dustin/go-humanize v1.0.1
-	github.com/evanw/esbuild v0.28.0
+	github.com/evanw/esbuild v0.28.1
 	github.com/fatih/color v1.18.0
 	github.com/fortytw2/leaktest v1.3.0
 	github.com/frankban/quicktest v1.14.6
diff --git a/go.sum b/go.sum
index 218df97c1..c89317796 100644
--- a/go.sum
+++ b/go.sum
@@ -237,6 +237,8 @@ github.com/envoyproxy/protoc-gen-validate v1.3.0 h1:TvGH1wof4H33rezVKWSpqKz5NXWg
 github.com/envoyproxy/protoc-gen-validate v1.3.0/go.mod h1:HvYl7zwPa5mffgyeTUHA9zHIH36nmrm7oCbo4YKoSWA=
 github.com/evanw/esbuild v0.28.0 h1:V96ghtc5p5JnNUQIUsc5H3kr+AcFcMqOJll2ZmJW6Lo=
 github.com/evanw/esbuild v0.28.0/go.mod h1:D2vIQZqV/vIf/VRHtViaUtViZmG7o+kKmlBfVQuRi48=
+github.com/evanw/esbuild v0.28.1 h1:ds+yuRyUaZGx++GR56CrCeuXh8PVhVM4xq8v7PNELFc=
+github.com/evanw/esbuild v0.28.1/go.mod h1:D2vIQZqV/vIf/VRHtViaUtViZmG7o+kKmlBfVQuRi48=
 github.com/fatih/color v1.18.0 h1:S8gINlzdQ840/4pfAwic/ZE0djQEH3wM94VfqLTZcOM=
 github.com/fatih/color v1.18.0/go.mod h1:4FelSpRwEGDpQ12mAdzqdOukCy4u8WUtOY6lkT/6HfU=
 github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
diff --git a/internal/js/esbuild/batch_integration_test.go b/internal/js/esbuild/batch_integration_test.go
index 16309985c..ca85cb4a7 100644
--- a/internal/js/esbuild/batch_integration_test.go
+++ b/internal/js/esbuild/batch_integration_test.go
@@ -243,8 +243,8 @@ Defer:
 `
 	b := hugolib.Test(t, files, hugolib.TestOptWithOSFs())
 	b.AssertPublishDir(
-		"en/mybatch/chunk-TOZKWCDE.js", "en/mybatch/mygroup.js ",
-		"fr/mybatch/mygroup.js", "fr/mybatch/chunk-TOZKWCDE.js")
+		"en/mybatch/chunk-MO3Q4WT6.js", "en/mybatch/mygroup.js ",
+		"fr/mybatch/mygroup.js", "fr/mybatch/chunk-MO3Q4WT6.js")
 }
 
 func TestBatchRenameBundledScript(t *testing.T) {
@@ -402,7 +402,7 @@ export default function P1Script() {};
 	b.AssertFileContent("public/mybatch/mygroup.js", "sourceMappingURL=mygroup.js.map")
 	b.AssertFileContent("public/mybatch/p1.js", "sourceMappingURL=p1.js.map")
 	b.AssertFileContent("public/mybatch/mygroup_run_runner.js", "sourceMappingURL=mygroup_run_runner.js.map")
-	b.AssertFileContent("public/mybatch/chunk-UQKPPNA6.js", "sourceMappingURL=chunk-UQKPPNA6.js.map")
+	b.AssertFileContent("public/mybatch/chunk-3REXYBSZ.js", "sourceMappingURL=chunk-3REXYBSZ.js.map")
 
 	checkMap := func(p string, expectLen int) {
 		s := b.FileContent(p)
@@ -421,7 +421,7 @@ export default function P1Script() {};
 	checkMap("public/mybatch/mygroup.js.map", 1)
 	checkMap("public/mybatch/p1.js.map", 1)
 	checkMap("public/mybatch/mygroup_run_runner.js.map", 0)
-	checkMap("public/mybatch/chunk-UQKPPNA6.js.map", 1)
+	checkMap("public/mybatch/chunk-3REXYBSZ.js.map", 1)
 }
 
 func TestBatchErrorRunnerResourceNotSet(t *testing.T) {
diff --git a/internal/js/esbuild/build.go b/internal/js/esbuild/build.go
index 355732503..779b112e0 100644
--- a/internal/js/esbuild/build.go
+++ b/internal/js/esbuild/build.go
@@ -217,7 +217,12 @@ func (c *BuildClient) Build(opts Options) (api.BuildResult, error) {
 			}
 
 			if !strings.HasPrefix(s, PrefixHugoVirtual) {
-				if !filepath.IsAbs(s) {
+				// A leading slash marks a synthetic import key rooted in Hugo's
+				// virtual namespace (see paths.AddLeadingSlash in batch.go); it is
+				// not an OutDir-relative path. filepath.IsAbs only reports true for
+				// such paths on Unix, so check it explicitly to behave the same on
+				// Windows.
+				if !filepath.IsAbs(s) && !strings.HasPrefix(s, "/") {
 					s = filepath.Join(opts.OutDir, s)
 				}
 			}