diff --git a/debian/rules.d/2-binary-arch.mk b/debian/rules.d/2-binary-arch.mk
index c720cc88041c..b90e26df1e8d 100644
--- a/debian/rules.d/2-binary-arch.mk
+++ b/debian/rules.d/2-binary-arch.mk
@@ -87,15 +87,15 @@ define install_control =
 	done
 endef
 
-# Ensure the directory prefix is exactly 100 characters long so pathnames are the
+# Ensure the directory prefix is exactly 140 characters long so pathnames are the
 # exact same length in any binary files produced by the builds.  These will be
 # commonised later.
 dkms_20d=....................
-dkms_100d=$(dkms_20d)$(dkms_20d)$(dkms_20d)$(dkms_20d)$(dkms_20d)
-dkms_100c=$(shell echo '$(dkms_100d)' | sed -e 's/\./_/g')
+dkms_140d=$(dkms_20d)$(dkms_20d)$(dkms_20d)$(dkms_20d)$(dkms_20d)$(dkms_20d)$(dkms_20d)
+dkms_140c=$(shell echo '$(dkms_140d)' | sed -e 's/\./_/g')
 define dkms_dir_prefix =
-$(shell echo $(1)/$(dkms_100c) | \
-	sed -e 's/\($(dkms_100d)\).*/\1/' -e 's/^\(.*\)....$$/\1dkms/')
+$(shell echo $(1)/$(dkms_140c) | \
+	sed -e 's/\($(dkms_140d)\).*/\1/' -e 's/^\(.*\)....$$/\1dkms/')
 endef
 
 # Install the finished build