diff --git a/cfg.mk b/cfg.mk
index 4a53f2bb28..8a444d646c 100644
--- a/cfg.mk
+++ b/cfg.mk
@@ -917,6 +917,12 @@ sc_prohibit_windows_special_chars_in_filename:
 	test -n "$$files" && { echo '$(ME): Windows special chars'     \
 	  'in filename not allowed:' 1>&2; echo $$files 1>&2; exit 1; } || :
 
+sc_prohibit_mixed_case_abbreviations:
+	@prohibit='Pci|Usb|Scsi'			\
+	in_vc_files='\.[ch]$$'				\
+	halt='Use PCI, USB, SCSI, not Pci, Usb, Scsi'	\
+	  $(_sc_search_regexp)
+
 # We don't use this feature of maint.mk.
 prev_version_file = /dev/null
 
@@ -1089,3 +1095,6 @@ exclude_file_name_regexp--sc_prohibit_getenv = \
 
 exclude_file_name_regexp--sc_avoid_attribute_unused_in_header = \
   ^src/util/virlog\.h$$
+
+exclude_file_name_regexp--sc_prohibit_mixed_case_abbreviations = \
+  ^src/(vbox/vbox_CAPI.*.h|esx/esx_vi.(c|h)|esx/esx_storage_backend_iscsi.c)$$