diff --git i/lib/matplotlib/ticker.py w/lib/matplotlib/ticker.py
index 4c33e8c9af..5cb1ca6746 100644
--- i/lib/matplotlib/ticker.py
+++ w/lib/matplotlib/ticker.py
@@ -964,7 +964,7 @@ class LogFormatter(Formatter):
             # It's probably a colorbar with
             # a format kwarg setting a LogFormatter in the manner
             # that worked with 1.5.x, but that doesn't work now.
-            self._sublabels = {1}  # label powers of base
+            self._sublabels = np.array([1])  # label powers of base
             return
 
         b = self._base
@@ -995,17 +995,16 @@ class LogFormatter(Formatter):
 
         if numticks > self.minor_thresholds[0]:
             # Label only bases
-            self._sublabels = {1}
+            self._sublabels = np.array([1])
         elif numdec > self.minor_thresholds[1]:
             # Add labels between bases at log-spaced coefficients;
             # include base powers in case the locations include
             # "major" and "minor" points, as in colorbar.
-            c = np.geomspace(1, b, int(b)//2 + 1)
-            self._sublabels = set(np.round(c))
+            self._sublabels = np.geomspace(1, b, int(b)//2 + 1).round()
             # For base 10, this yields (1, 2, 3, 4, 6, 10).
         else:
             # Label all integer multiples of base**n.
-            self._sublabels = set(np.arange(1, b + 1))
+            self._sublabels = np.arange(1, b + 1)
 
     def _num_to_string(self, x, vmin, vmax):
         return self._pprint_val(x, vmax - vmin) if 1 <= x <= 10000 else f"{x:1.0e}"
@@ -1021,11 +1020,10 @@ class LogFormatter(Formatter):
         fx = math.log(x) / math.log(b)
         is_x_decade = _is_close_to_int(fx)
         exponent = round(fx) if is_x_decade else np.floor(fx)
-        coeff = round(b ** (fx - exponent))
 
         if self.labelOnlyBase and not is_x_decade:
             return ''
-        if self._sublabels is not None and coeff not in self._sublabels:
+        if self._sublabels is not None and not np.isin(x, self._sublabels * b**exponent):
             return ''
 
         vmin, vmax = self.axis.get_view_interval()