diff --git a/startup-vxWorks b/startup-vxWorks
index 21030ee..378674f 100644
--- a/startup-vxWorks
+++ b/startup-vxWorks
@@ -1,7 +1,7 @@
 # totally generic vxWorks startup script
 
 #set ARCH according to vxWorks version and cpu type
-VX6=(*runtimeVersion>>24)&255-'5'
+VX6=(*runtimeVersion>>24)-'5'
 VMI=(*runtimeVersion>>8)&255
 ARCH=malloc(16)
 sprintf(ARCH,"%s%c-ppc60%d",VX6?"V6":"T",VX6?VMI:VMI>'3'?'2':'1',sysCpu-90)
diff --git a/startup.script_common b/startup.script_common
index 5848923..44c1f9b 100644
--- a/startup.script_common
+++ b/startup.script_common
@@ -10,7 +10,7 @@ EPICS_MODULES = "/ioc/modules"
 REQUIRE_VERSION="2.10.10"
 
 # Set EPICS_HOST_ARCH according to vxWorks version and cpu type
-VX6=(*runtimeVersion>>24)&255-'5'
+VX6=(*runtimeVersion>>24)-'5'
 VMI=(*runtimeVersion>>8)&255
 EPICS_HOST_ARCH=malloc(16)
 sprintf EPICS_HOST_ARCH, "%s%c-ppc60%d", VX6 ? "V6" : "T", VX6 ? VMI : VMI>'3' ? '2' : '1', sysCpu-90