diff --git a/src/greaseweazle/codec/codec.py b/src/greaseweazle/codec/codec.py
index cd8c4cb..539fb05 100644
--- a/src/greaseweazle/codec/codec.py
+++ b/src/greaseweazle/codec/codec.py
@@ -159,7 +159,7 @@ def full_prefix(self) -> str:
             if p.prefix:
                 s.insert(0, p.prefix)
             p = p.parent
-        return '.'.join(s) + '.' if s else ''
+        return ''.join(s)
 
 
 # Import the TrackDef subclasses
diff --git a/src/greaseweazle/data/diskdefs.cfg b/src/greaseweazle/data/diskdefs.cfg
index cddfc21..2afda42 100644
--- a/src/greaseweazle/data/diskdefs.cfg
+++ b/src/greaseweazle/data/diskdefs.cfg
@@ -42,31 +42,31 @@
 # Sub-files can be imported by "import [<prefix>] "<file>"". Any definition
 # names from the imported file will be prefixed by the optional <prefix>.
 
-import acorn "diskdefs_acorn.cfg"
-import akai "diskdefs_akai.cfg"
-import amiga "diskdefs_amiga.cfg"
-import apple2 "diskdefs_apple2.cfg"
-import atari "diskdefs_atari.cfg"
-import atarist "diskdefs_atarist.cfg"
-import coco "diskdefs_coco.cfg"
-import commodore "diskdefs_commodore.cfg"
-import dec "diskdefs_dec.cfg"
-import dragon "diskdefs_dragon.cfg"
-import ensoniq "diskdefs_ensoniq.cfg"
-import epson "diskdefs_epson.cfg"
-import gem "diskdefs_gem.cfg"
-import hp "diskdefs_hp.cfg"
-import ibm "diskdefs_ibm.cfg"
-import mac "diskdefs_mac.cfg"
-import mm1 "diskdefs_mm1.cfg"
-import msx "diskdefs_msx.cfg"
-import northstar "diskdefs_northstar.cfg"
-import occ1 "diskdefs_occ1.cfg"
-import olivetti "diskdefs_olivetti.cfg"
-import pc98 "diskdefs_pc98.cfg"
-import raw "diskdefs_raw.cfg"
-import sci "diskdefs_sci.cfg"
-import sega "diskdefs_sega.cfg"
-import thomson "diskdefs_thomson.cfg"
-import tsc "diskdefs_tsc.cfg"
-import zx "diskdefs_zx.cfg"
+import acorn. "diskdefs_acorn.cfg"
+import akai. "diskdefs_akai.cfg"
+import amiga. "diskdefs_amiga.cfg"
+import apple2. "diskdefs_apple2.cfg"
+import atari. "diskdefs_atari.cfg"
+import atarist. "diskdefs_atarist.cfg"
+import coco. "diskdefs_coco.cfg"
+import commodore. "diskdefs_commodore.cfg"
+import dec. "diskdefs_dec.cfg"
+import dragon. "diskdefs_dragon.cfg"
+import ensoniq. "diskdefs_ensoniq.cfg"
+import epson. "diskdefs_epson.cfg"
+import gem. "diskdefs_gem.cfg"
+import hp. "diskdefs_hp.cfg"
+import ibm. "diskdefs_ibm.cfg"
+import mac. "diskdefs_mac.cfg"
+import mm1. "diskdefs_mm1.cfg"
+import msx. "diskdefs_msx.cfg"
+import northstar. "diskdefs_northstar.cfg"
+import occ1. "diskdefs_occ1.cfg"
+import olivetti. "diskdefs_olivetti.cfg"
+import pc98. "diskdefs_pc98.cfg"
+import raw. "diskdefs_raw.cfg"
+import sci. "diskdefs_sci.cfg"
+import sega. "diskdefs_sega.cfg"
+import thomson. "diskdefs_thomson.cfg"
+import tsc. "diskdefs_tsc.cfg"
+import zx. "diskdefs_zx.cfg"