diff --git a/src/pypfilt/state.py b/src/pypfilt/state.py
index 47265a401ad9a95ec96f086b85d43ab4b9e3272f..b22f0bf55135a9cbcfd1e0feb22e1583fb6cf852 100644
--- a/src/pypfilt/state.py
+++ b/src/pypfilt/state.py
@@ -171,7 +171,7 @@ def earlier_states(hist, ix, steps):
     # Don't go too far back (negative indices jump into the future).
     if steps > ix:
         msg_fmt = 'Cannot look back {} time-steps, will look back {}'
-        logger.warn(msg_ftm.format(steps, ix))
+        logger.warn(msg_fmt.format(steps, ix))
     steps = min(steps, ix)
 
     # Start with the parent indices for the current particles, which allow us