diff --git a/src/taggingbackends/features/skeleton.py b/src/taggingbackends/features/skeleton.py
index 959094ae95f9089d0edbc0d97597e8de6aaee599..e4e9539ae9f1edaf16e687ab7fcfa9443f99720d 100644
--- a/src/taggingbackends/features/skeleton.py
+++ b/src/taggingbackends/features/skeleton.py
@@ -48,10 +48,10 @@ def interpolate(times, spines, anchor, window_length,
     grid = range(istart, istop+1)
     series = []
     for i in grid:
-        t = round((anchor + i * frame_interval) * 1e4) * 1e-4
+        t = np.trunc((anchor + i * frame_interval) * 1e4) * 1e-4
         inext = np.flatnonzero(t <= times)[0]
         tnext, xnext = times[inext], spines[inext]
-        if tnext == t:
+        if tnext - t < 1e-4:
             x = xnext
         else:
             assert 0 < inext