diff --git a/src/tsconfig.strictNullChecks.json b/src/tsconfig.strictNullChecks.json
index 94efaf2e613..3aadf72d718 100644
--- a/src/tsconfig.strictNullChecks.json
+++ b/src/tsconfig.strictNullChecks.json
@@ -641,6 +641,7 @@
 		"./vs/workbench/parts/snippets/test/electron-browser/snippetsRegistry.test.ts",
 		"./vs/workbench/parts/snippets/test/electron-browser/snippetsRewrite.test.ts",
 		"./vs/workbench/parts/snippets/test/electron-browser/snippetsService.test.ts",
+		"./vs/workbench/parts/splash/electron-browser/partsSplash.contribution.ts",
 		"./vs/workbench/parts/stats/node/stats.contribution.ts",
 		"./vs/workbench/parts/stats/node/workspaceStats.ts",
 		"./vs/workbench/parts/stats/test/workspaceStats.test.ts",
diff --git a/src/vs/workbench/parts/splash/electron-browser/partsSplash.contribution.ts b/src/vs/workbench/parts/splash/electron-browser/partsSplash.contribution.ts
index 3a61bf4ac74..2bf9f241d7b 100644
--- a/src/vs/workbench/parts/splash/electron-browser/partsSplash.contribution.ts
+++ b/src/vs/workbench/parts/splash/electron-browser/partsSplash.contribution.ts
@@ -27,7 +27,7 @@ class PartsSplash {
 	private readonly _disposables: IDisposable[] = [];
 
 	private _lastBaseTheme: string;
-	private _lastBackground: string;
+	private _lastBackground?: string;
 
 	constructor(
 		@IThemeService private readonly _themeService: IThemeService,
@@ -85,7 +85,7 @@ class PartsSplash {
 		}
 	}
 
-	private _getThemeColor(id: ColorIdentifier): string {
+	private _getThemeColor(id: ColorIdentifier): string | undefined {
 		const theme = this._themeService.getTheme();
 		const color = theme.getColor(id);
 		return color ? color.toString() : undefined;