@@ -1,5 +1,8 @@
 # Changelog
 
+## 9.5.1
+* [fix: inputSourceMap can be null](https://github.com/TypeStrong/ts-loader/pull/1639) [#1638] - thanks @johnnyreilly and @michaeltford
+
 ## 9.5.0
 * [Feature: map the input source map in case ts-loader is used in a loader pipeline](https://github.com/TypeStrong/ts-loader/pull/1626) - thanks @Ka0o0 and @bojanv55
 
 
@@ -1,6 +1,6 @@
 {
   "name": "ts-loader",
-  "version": "9.5.0",
+  "version": "9.5.1",
   "description": "TypeScript loader for webpack",
   "main": "index.js",
   "types": "dist",
 
@@ -149,7 +149,7 @@ function makeSourceMapAndFinish(
   // in the first case, we simply return undefined.
   // in the second case we only need to return the newly generated source map
   // this avoids that we have to make a possibly expensive call to the source-map lib
-  if (sourceMap === undefined || inputSourceMap === undefined) {
+  if (sourceMap === undefined || !inputSourceMap) {
     callback(null, output, sourceMap);
     return;
   }
Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,6 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "ts-loader",`
`3`		`- "version": "9.5.0",`
	`3`	`+ "version": "9.5.1",`
`4`	`4`	`"description": "TypeScript loader for webpack",`
`5`	`5`	`"main": "index.js",`
`6`	`6`	`"types": "dist",`
Original file line number	Diff line number	Diff line change
`@@ -149,7 +149,7 @@ function makeSourceMapAndFinish(`
`149`	`149`	`// in the first case, we simply return undefined.`
`150`	`150`	`// in the second case we only need to return the newly generated source map`
`151`	`151`	`// this avoids that we have to make a possibly expensive call to the source-map lib`
`152`		`- if (sourceMap === undefined \|\| inputSourceMap === undefined) {`
	`152`	`+ if (sourceMap === undefined \|\| !inputSourceMap) {`
`153`	`153`	`callback(null, output, sourceMap);`
`154`	`154`	`return;`
`155`	`155`	`}`