Why did Mussolini prevent Hitler from taking Austria?

[HansvonLuck]

Before the actual Anschluss in 1938, there was another event in which Hitler wanted to annex Austria.

Nobody really opposed him except for Mussolini. He was firmly opposed in the annexation of Austria. Why was that? Was it because he was afraid that Hitler might come too near to the Italien border?

[Davide Pastore]

Why was that? Was it because he was afraid that Hitler might come too near to the Italien border?

Italy fought a long and costly series of wars between 1848 and 1918 to eradicate German-speaking people from inside Italian natural borders.
The most important result of 1918 peace was not the liberation of Trento and Trieste, but the destruction of the historical enemy, the Habsburg empire, and the creation in its place of a series of weak buffer states along Italian border (Austria, Yugoslavia). After Anschluss, Italy had again a much-too-strong German-speaking nation unconfortably near (as 1943 will show, too near). A further proof that Mussolini (who in 1938 did NOT object) was a fool.

Davide