diff --git a/src/greaseweazle/track.py b/src/greaseweazle/track.py
index 537bbaf5..37929ffe 100644
--- a/src/greaseweazle/track.py
+++ b/src/greaseweazle/track.py
@@ -168,9 +168,10 @@ def _flux(self, for_writeout, cue_at_index) -> Union[Flux, WriteoutFlux]:
         ticks_to_index = sum(bit_ticks)
 
         # Weak regions need special processing for correct flux representation.
-        for s,n in self.weak:
+        for s, n in self.weak:
+            if n < 2: continue # Too short to reliably weaken
             e = s + n
-            assert 0 < s < e <= bitlen
+            assert 0 <= s < e <= bitlen
             pattern = bitarray(endian="big")
             if n < 400 or self.force_random_weak:
                 # Short weak regions are written with no flux transitions.