diff --git a/lib/components/src/blocks/Source.tsx b/lib/components/src/blocks/Source.tsx
index 582801087ed6..831f8057748e 100644
--- a/lib/components/src/blocks/Source.tsx
+++ b/lib/components/src/blocks/Source.tsx
@@ -69,4 +69,7 @@ const Source: FunctionComponent<SourceProps> = props => {
   return <ThemeProvider theme={convert(overrideTheme)}>{syntaxHighlighter}</ThemeProvider>;
 };
 
+Source.defaultProps = {
+  format: false,
+};
 export { Source };