--- a/XWorkstation.st	Tue Jul 17 08:03:06 2018 +0200
+++ b/XWorkstation.st	Thu Jul 19 20:54:26 2018 +0100
@@ -9517,7 +9517,7 @@
     super initializeScreenProperties.
 
     hasShapeExtension := self hasExtension:#SHAPE.
-    hasShmExtension := self hasExtension:#MIT_SHM.
+    hasShmExtension := self hasExtension:#'MIT-SHM'.
     hasDPSExtension := self hasExtension:#DPS.
     hasXVideoExtension := self hasExtension:#XVideo.
     hasMbufExtension := self hasExtension:#'Multi-Buffering'.