diff --git a/declarations.d.ts b/declarations.d.ts
index bab2f6008..0aa48818c 100644
--- a/declarations.d.ts
+++ b/declarations.d.ts
@@ -81,7 +81,7 @@ declare module "@webassemblyjs/ast" {
 	export class TypeInstruction extends Node {}
 	export class IndexInFuncSection extends Node {}
 	export function indexLiteral(index: number): IndexLiteral;
-	export function numberLiteral(num: number): NumberLiteral;
+	export function numberLiteralFromRaw(num: number): NumberLiteral;
 	export function global(globalType: string, nodes: Node[]): Global;
 	export function identifier(indentifier: string): Identifier;
 	export function funcParam(valType: string, id: Identifier): FuncParam;
diff --git a/lib/wasm/WebAssemblyGenerator.js b/lib/wasm/WebAssemblyGenerator.js
index ba9a232bc..7afb2648e 100644
--- a/lib/wasm/WebAssemblyGenerator.js
+++ b/lib/wasm/WebAssemblyGenerator.js
@@ -9,6 +9,7 @@ const Template = require("../Template");
 const WebAssemblyUtils = require("./WebAssemblyUtils");
 const { RawSource } = require("webpack-sources");
 
+const { shrinkPaddedLEB128 } = require("@webassemblyjs/wasm-opt");
 const { editWithAST, addWithAST } = require("@webassemblyjs/wasm-edit");
 const { decode } = require("@webassemblyjs/wasm-parser");
 const t = require("@webassemblyjs/ast");
@@ -16,6 +17,21 @@ const t = require("@webassemblyjs/ast");
 /** @typedef {import("../Module")} Module */
 /** @typedef {import("./WebAssemblyUtils").UsedWasmDependency} UsedWasmDependency */
 
+/**
+ * @typedef {(ArrayBuffer) => ArrayBuffer} ArrayBufferTransform
+ */
+
+/**
+ * Run some preprocessing on the binary before wasm-edit
+ *
+ * @param {ArrayBuffer} ab - original binary
+ * @returns {ArrayBufferTransform} transform
+ */
+function preprocess(ab) {
+	const optBin = shrinkPaddedLEB128(new Uint8Array(ab));
+	return optBin.buffer;
+}
+
 /**
  * @template T
  * @param {Function[]} fns transforms
@@ -42,9 +58,6 @@ const isGlobalImport = n => n.descr.type === "GlobalType";
 const isFuncImport = n => n.descr.type === "FuncImportDescr";
 
 // TODO replace with @callback
-/**
- * @typedef {(ArrayBuffer) => ArrayBuffer} ArrayBufferTransform
- */
 
 /**
  * Removes the start instruction
@@ -176,7 +189,7 @@ const rewriteImportedGlobals = state => bin => {
 
 				newGlobals.push(
 					t.global(globalType, [
-						t.objectInstruction("const", "i32", [t.numberLiteral(0)])
+						t.objectInstruction("const", "i32", [t.numberLiteralFromRaw(0)])
 					])
 				);
 
@@ -315,7 +328,8 @@ const getUsedDependencyMap = module => {
 
 class WebAssemblyGenerator extends Generator {
 	generate(module) {
-		const bin = module.originalSource().source();
+		let bin = module.originalSource().source();
+		bin = preprocess(bin);
 
 		const initFuncId = t.identifier(
 			Array.isArray(module.usedExports)
diff --git a/package.json b/package.json
index 09df29240..2cb009c11 100644
--- a/package.json
+++ b/package.json
@@ -7,6 +7,7 @@
   "dependencies": {
     "@webassemblyjs/ast": "1.5.3",
     "@webassemblyjs/wasm-edit": "1.5.3",
+    "@webassemblyjs/wasm-opt": "1.5.3",
     "@webassemblyjs/wasm-parser": "1.5.3",
     "acorn": "^5.0.0",
     "acorn-dynamic-import": "^3.0.0",