diff --git a/src/sage/categories/sets_cat.py b/src/sage/categories/sets_cat.py
index 54563076db3..459bf9a882b 100644
--- a/src/sage/categories/sets_cat.py
+++ b/src/sage/categories/sets_cat.py
@@ -2165,7 +2165,10 @@ def __iter__(self):
                 # visualize an odometer, with "wheels" displaying "digits"...:
                 factors = list(self.cartesian_factors())
                 wheels = [iter(f) for f in factors]
-                digits = [next(it) for it in wheels]
+                try:
+                    digits = [next(it) for it in wheels]
+                except StopIteration:
+                    return
                 while True:
                     yield self._cartesian_product_of_elements(digits)
                     for i in range(len(digits)-1, -1, -1):
@@ -2174,7 +2177,10 @@ def __iter__(self):
                             break
                         except StopIteration:
                             wheels[i] = iter(factors[i])
-                            digits[i] = next(wheels[i])
+                            try:
+                                digits[i] = next(wheels[i])
+                            except StopIteration:
+                                return
                     else:
                         break
 
diff --git a/src/sage/combinat/finite_state_machine.py b/src/sage/combinat/finite_state_machine.py
index 59626ba771c..3b666e2f84b 100644
--- a/src/sage/combinat/finite_state_machine.py
+++ b/src/sage/combinat/finite_state_machine.py
@@ -13701,8 +13701,8 @@ def compare_to_tape(self, track_number, word):
         it_word = iter(word)
 
         # check letters in cache
-        if any(letter_on_track != next(it_word)
-               for letter_on_track in track_cache):
+        if any(letter_on_track != letter_in_word
+               for letter_on_track, letter_in_word in zip(track_cache, it_word)):
             return False
 
         # check letters not already cached