diff --git a/Lib/configparser.py b/Lib/configparser.py
index 7bc4398..9d5f779 100644
--- a/Lib/configparser.py
+++ b/Lib/configparser.py
@@ -993,18 +993,26 @@
         indent_level = 0
         e = None                              # None, or an exception
         for lineno, line in enumerate(fp, start=1):
-            comment_start = None
+            comment_start = sys.maxsize
             # strip inline comments
-            for prefix in self._inline_comment_prefixes:
-                index = line.find(prefix)
-                if index == 0 or (index > 0 and line[index-1].isspace()):
-                    comment_start = index
-                    break
+            inline_prefixes = {p: -1 for p in self._inline_comment_prefixes}
+            while comment_start == sys.maxsize and inline_prefixes:
+                next_prefixes = {}
+                for prefix, index in inline_prefixes.items():
+                    index = line.find(prefix, index+1)
+                    if index == -1:
+                        continue
+                    next_prefixes[prefix] = index
+                    if index == 0 or (index > 0 and line[index-1].isspace()):
+                        comment_start = min(comment_start, index)
+                inline_prefixes = next_prefixes
             # strip full line comments
             for prefix in self._comment_prefixes:
                 if line.strip().startswith(prefix):
                     comment_start = 0
                     break
+            if comment_start == sys.maxsize:
+                comment_start = None
             value = line[:comment_start].strip()
             if not value:
                 if self._empty_lines_in_values: