diff --git a/build.sbt b/build.sbt
index 27a8fe60e..35fc76bd4 100644
--- a/build.sbt
+++ b/build.sbt
@@ -249,9 +249,11 @@ lazy val buildNpmPackageTask = Def.task {
   val licenseFile = new File("js/npm/LICENSE")
   val readMeFile = new File("js/npm/README.md")
   val packageJsonFile = new File("js/npm/package.json")
+  val warnFile = new File("js/npm/warn-about-constructor-bc-break.js")
 
   Files.copy(new File("LICENSE").toPath, licenseFile.toPath)
   Files.copy(new File("js/README.md").toPath, readMeFile.toPath)
+  Files.copy(new File("js/warn-about-constructor-bc-break.js").toPath, warnFile.toPath)
 
   val packageJsonTmpl = IO.read(new File("js/package.json"), UTF8)
   val packageJsonContents = packageJsonTmpl.replaceFirst(
@@ -264,6 +266,7 @@ lazy val buildNpmPackageTask = Def.task {
   Seq(
     licenseFile,
     readMeFile,
-    packageJsonFile
+    packageJsonFile,
+    warnFile,
   )
 }
diff --git a/js/package.json b/js/package.json
index 599c10631..db38f1a72 100644
--- a/js/package.json
+++ b/js/package.json
@@ -33,6 +33,7 @@
     "url": "git+https://github.com/kaitai-io/kaitai_struct_compiler.git"
   },
   "scripts": {
+    "postinstall": "node warn-about-constructor-bc-break.js",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "version": "OVERRIDDEN BY /build.sbt"
diff --git a/js/warn-about-constructor-bc-break.js b/js/warn-about-constructor-bc-break.js
new file mode 100644
index 000000000..df40ed111
--- /dev/null
+++ b/js/warn-about-constructor-bc-break.js
@@ -0,0 +1,5 @@
+console.warn(
+'kaitai-struct-compiler: WARNING - you\'ve just installed the 0.11.0+ version. \
+If you\'re coming from an older version, make sure to update your code - \
+the usage changed from "(new KaitaiStructCompiler()).compile(...)" to "KaitaiStructCompiler.compile(...)"'
+);