diff --git a/whisper/decoding.py b/whisper/decoding.py
index 81cd845..2592ba9 100644
--- a/whisper/decoding.py
+++ b/whisper/decoding.py
@@ -471,6 +471,13 @@ class ApplyTimestampRules(LogitFilter):
                 # timestamps shouldn't decrease; forbid timestamp tokens smaller than the last
                 logits[k, self.tokenizer.timestamp_begin : timestamps[-1]] = -np.inf
 
+                # to force that timestamps are strictly increasing
+                if last_was_timestamp and not penultimate_was_timestamp:
+                    timestamp_last = timestamps[-1]
+                else:
+                    timestamp_last = timestamps[-1] + 1
+                logits[k, self.tokenizer.timestamp_begin : timestamp_last] = -np.inf
+
         if tokens.shape[1] == self.sample_begin:
             # suppress generating non-timestamp tokens at the beginning
             logits[:, : self.tokenizer.timestamp_begin] = -np.inf