diff --git a/PyInstaller/depend/utils.py b/PyInstaller/depend/utils.py
index baffb2a9f3a..95846f39d53 100644
--- a/PyInstaller/depend/utils.py
+++ b/PyInstaller/depend/utils.py
@@ -399,6 +399,18 @@ def load_ldconfig_cache():
     for line in text:
         # :fixme: this assumes libary names do not contain whitespace
         m = pattern.match(line)
+
+        # Sanitize away any abnormal lines of output.
+        if m is None:
+            # Warn about it then skip the rest of this iteration.
+            if re.search("Cache generated by:", line):
+                # See #5540. This particular line is harmless.
+                pass
+            else:
+                logger.warning(
+                    "Unrecognised line of output %r from ldconfig", line)
+            continue
+
         path = m.groups()[-1]
         if is_freebsd or is_openbsd:
             # Insert `.so` at the end of the lib's basename. soname