diff --git a/src/support.js b/src/support.js
index 436809404..7f49516f8 100644
--- a/src/support.js
+++ b/src/support.js
@@ -273,7 +273,7 @@ jQuery.support = (function() {
 		}
 
 		container = document.createElement("div");
-		container.style.cssText = vb + "width:0;height:0;position:static;top:0;marginTop:" + conMarginTop + "px";
+		container.style.cssText = vb + "width:0;height:0;position:static;top:0;margin-top:" + conMarginTop + "px";
 		body.insertBefore( container, body.firstChild );
 
 		// Construct a test element