diff --git a/packages/material-ui/src/styles/createSpacing.d.ts b/packages/material-ui/src/styles/createSpacing.d.ts
index 8b00652ce093f5..f0787565bdf7a5 100644
--- a/packages/material-ui/src/styles/createSpacing.d.ts
+++ b/packages/material-ui/src/styles/createSpacing.d.ts
@@ -4,7 +4,7 @@ export type SpacingArgument = number | string;
 
 export interface Spacing {
   (): number;
-  (value: SpacingArgument): number;
+  (value: number): number;
   (topBottom: SpacingArgument, rightLeft: SpacingArgument): string;
   (top: SpacingArgument, rightLeft: SpacingArgument, bottom: SpacingArgument): string;
   (