diff --git a/src/build.ts b/src/build.ts
index 9730091..01b794e 100644
--- a/src/build.ts
+++ b/src/build.ts
@@ -431,12 +431,11 @@ class Builder {
     let mod = this.options.moduleStyle || "es"
 
     let gen = "// This file was generated by lezer-generator. You probably shouldn't edit it.\n", head = gen
-    head += mod == "cjs" ? `const {LRParser} = require("@lezer/lr")\n`
-      : `import {LRParser} from "@lezer/lr"\n`
     let imports: {[source: string]: string[]} = {}, imported: {[spec: string]: string} = Object.create(null)
-    let defined = Object.create(null)
+    let defined: {[name: string]: boolean} = Object.create(null)
+    for (let word of KEYWORDS) defined[word] = true
     let exportName = this.options.exportName || "parser"
-    defined.Parser = defined[exportName] = true
+    defined[exportName] = true
     let getName = (prefix: string) => {
       for (let i = 0;; i++) {
         let id = prefix + (i ? "_" + i : "")
@@ -444,7 +443,7 @@ class Builder {
       }
     }
 
-    let importName = (name: string, source: string, prefix: string) => {
+    let importName = (name: string, source: string, prefix: string = name) => {
       let spec = name + " from " + source
       if (imported[spec]) return imported[spec]
       let src = JSON.stringify(source), varName = name
@@ -452,9 +451,11 @@ class Builder {
         varName = getName(prefix)
         name += `${mod == "cjs" ? ":" : " as"} ${varName}`
       }
+      defined[varName] = true
       ;(imports[src] || (imports[src] = [])).push(name)
       return imported[spec] = varName
     }
+    let lrParser = importName("LRParser", "@lezer/lr")
 
     let tokenizers = rawTokenizers.map(tok => {
       if (tok instanceof ExternalTokenDeclaration) {
@@ -465,11 +466,11 @@ class Builder {
       }
     })
 
-    let context = this.ast.context ? importName(this.ast.context.id.name, this.ast.context.source, "cx") : null
+    let context = this.ast.context ? importName(this.ast.context.id.name, this.ast.context.source) : null
 
     let nodeProps = rawNodeProps.map(({prop, terms}) => {
       let {source} = this.knownProps[prop]
-      let propID = source.from ? importName(source.name, source.from, "prop") : JSON.stringify(source.name)
+      let propID = source.from ? importName(source.name, source.from) : JSON.stringify(source.name)
       return `[${propID}, ${terms.map(serializePropValue).join(",")}]`
     })
 
@@ -481,18 +482,19 @@ class Builder {
     let specHead = ""
     let specialized = rawSpecialized.map(v => {
       if (v instanceof ExternalSpecializer) {
-        let name = importName(v.ast.id.name, v.ast.source, v.ast.id.name)
+        let name = importName(v.ast.id.name, v.ast.source)
         return `{term: ${v.term!.id}, get: (value, stack) => (${name}(value, stack) << 1)${
           v.ast.type == "extend" ? ` | ${Specialize.Extend}` : ''}, external: ${name}${
           v.ast.type == "extend" ? ', extend: true' : ''}}`
       } else {
         let tableName = getName("spec_" + v.token.name.replace(/\W/g, ""))
+        defined[tableName] = true
         specHead += `const ${tableName} = ${specializationTableString(v.table)}\n`
         return `{term: ${v.token.id}, get: value => ${tableName}[value] || -1}`
       }
     })
 
-    let propSources = this.ast.externalPropSources.map(s => importName(s.id.name, s.source, "props"))
+    let propSources = this.ast.externalPropSources.map(s => importName(s.id.name, s.source))
 
     for (let source in imports) {
       if (mod == "cjs")
@@ -509,7 +511,7 @@ class Builder {
 
     let dialects = Object.keys(rawDialects).map(d => `${d}: ${rawDialects[d]}`)
 
-    let parserStr = `LRParser.deserialize({
+    let parserStr = `${lrParser}.deserialize({
   version: ${File.Version},
   states: ${encodeArray(states, 0xffffffff)},
   stateData: ${encodeArray(stateData)},