diff --git a/README.md b/README.md
index fc511dc..b59ba65 100644
--- a/README.md
+++ b/README.md
@@ -37,7 +37,7 @@ use responsibly.
 
 ```
 usage: impatient [-h] [-f FINAL] [-i INTERVAL] [-w WINDOW] [-d DECAY]
-                 (-p PATH | -c COMMAND)
+                 [-V FRACTION] [-I COUNT] [-l PATH] (-p PATH | -c COMMAND)
 
 Display progress and time estimates for arbitrary tasks
 
@@ -55,6 +55,20 @@ optional arguments:
                         Decay coefficient for older samples (default 1). Must
                         be between 0 and 1 inclusive. The lower this is, the
                         more responsive/swingy the estimate will be.
+  -V FRACTION, --termination-value-threshold FRACTION
+                        Fraction of the expected final value that must be
+                        reached in order to terminate (default 0.95). Reaching
+                        this threshold is necessary but not sufficient, see
+                        also -I
+  -I COUNT, --termination-inactivity-threshold COUNT
+                        Number of consecutive unchanged samples that must be
+                        observed in order to terminate (default 10). Reaching
+                        this threshold is necessary but not sufficient, see
+                        also -V
+  -l PATH, --log-file PATH
+                        File to log the time series to. Will be saved as a
+                        csv, with columns for timestamp and for value. Will
+                        append data if the file already exists.
   -p PATH, --path PATH  Track total disk usage of a given path
   -c COMMAND, --command COMMAND
                         Track value returned by a shell command; this should
diff --git a/impatient b/impatient
index b285cf7..0240e7e 100755
--- a/impatient
+++ b/impatient
@@ -132,6 +132,11 @@ while True:
             ), end='')
     sys.stdout.flush()
 
-    if final and current >= args.termination_value_threshold*final and all(d == 0 for d in deltas[-args.termination_inactivity_threshold:]):
+    if (
+        final
+        and current >= args.termination_value_threshold*final
+        and len(deltas) >= args.termination_inactivity_threshold
+        and all(d == 0 for d in deltas[-args.termination_inactivity_threshold:])
+    ):
         print()
         break