--- a/client.mk
+++ b/client.mk
@@ -624,17 +624,23 @@ endif
 # CVS defines for the C LDAP SDK
 #
 LDAPCSDK_CO_MODULE = mozilla/directory/c-sdk
 LDAPCSDK_CO_FLAGS := -P
 ifdef MOZ_CO_FLAGS
   LDAPCSDK_CO_FLAGS := $(MOZ_CO_FLAGS)
 endif
 LDAPCSDK_CO_FLAGS := $(LDAPCSDK_CO_FLAGS) $(if $(LDAPCSDK_CO_TAG),-r $(LDAPCSDK_CO_TAG),-A)
+
+# Can only pull the tip or branch tags by date
+ifeq (,$(filter-out HEAD %BRANCH,$(LDAPCSDK_CO_TAG)))
 CVSCO_LDAPCSDK = $(CVS) $(CVS_FLAGS) co $(LDAPCSDK_CO_FLAGS) $(CVS_CO_DATE_FLAGS) $(LDAPCSDK_CO_MODULE)
+else
+CVSCO_LDAPCSDK = $(CVS) $(CVS_FLAGS) co $(LDAPCSDK_CO_FLAGS) $(LDAPCSDK_CO_MODULE)
+endif
 
 ####################################
 # Error on obsolete variables.
 #
 
 ifdef MOZ_MAPINFO
 $(warning MOZ_MAPINFO is obsolete, use MOZ_CO_MODULE=mozilla/tools/codesighs instead.)
 MOZ_MODULE_LIST += mozilla/tools/codesighs