diff --git a/src/vs/base/common/htmlContent.ts b/src/vs/base/common/htmlContent.ts
index ab7ae6065f19d6081b7156747950e27c2367f172..ce013b916cc6e5d945f95989a7c6bcd5f6261d6f 100644
--- a/src/vs/base/common/htmlContent.ts
+++ b/src/vs/base/common/htmlContent.ts
@@ -56,7 +56,7 @@ export function isEmptyMarkdownString(oneOrMany: IMarkdownString | IMarkdownStri
export function isMarkdownString(thing: any): thing is IMarkdownString {
if (thing instanceof MarkdownString) {
return true;
- } else if (typeof thing === 'object') {
+ } else if (thing && typeof thing === 'object') {
return typeof (thing).value === 'string'
&& (typeof (thing).isTrusted === 'boolean' || (thing).isTrusted === void 0);
}
diff --git a/src/vs/workbench/api/node/extHostTypeConverters.ts b/src/vs/workbench/api/node/extHostTypeConverters.ts
index aa6a0d2b7d5eb6483800248f4224477e26a2f2b8..d8aef198fd88f9b197432241a55ee35ea6737beb 100644
--- a/src/vs/workbench/api/node/extHostTypeConverters.ts
+++ b/src/vs/workbench/api/node/extHostTypeConverters.ts
@@ -158,7 +158,7 @@ export namespace MarkdownString {
}
function isCodeblock(thing: any): thing is Codeblock {
- return typeof thing === 'object'
+ return thing && typeof thing === 'object'
&& typeof (thing).language === 'string'
&& typeof (thing).value === 'string';
}