diff --git a/.github/workflows/lib_compat_test.py b/.github/workflows/lib_compat_test.py
index 25ce685..10460cc 100755
--- a/.github/workflows/lib_compat_test.py
+++ b/.github/workflows/lib_compat_test.py
@@ -19,21 +19,18 @@ args = parser.parse_args()
 # Parses GLIBC_2.3 into ("GLIBC", [2,3])
 # Parses GLIBC into ("GLIBC", None)
 def parse_version(version):
-  parts = version.split('_', 1)
+  parts = version.rsplit('_', 1)
   if len(parts) == 1:
     return (version, None)
-  return (parts[0], [int(p) for p in parts[1].split('.')])
+  try:
+    return (parts[0], [int(p) for p in parts[1].split('.')])
+  except ValueError:
+    return (version, None)
 
 lib_versions = dict([parse_version(v) for v in args.lib])
 
-# Determines whether an optionally-versioned symbol is acceptable.
-def accept_symbol(sym):
-  if sym in args.sym:
-    return True
-  split = sym.split('@', 1)
-  return (split[0] in args.sym) or (len(split) == 2 and accept_lib(split[1]))
-
 # Determines whether all symbols with version 'lib' are acceptable.
+# A versioned library is name_x.y.z by convention.
 def accept_lib(lib):
   (lib, ver) = parse_version(lib)
   if not lib in lib_versions: # Non-whitelisted library.
@@ -44,6 +41,14 @@ def accept_lib(lib):
     return False
   return ver <= lib_versions[lib]
 
+# Determines whether an optionally-versioned symbol is acceptable.
+# A versioned symbol is symbol@version as output by nm.
+def accept_symbol(sym):
+  if sym in args.sym:
+    return True
+  split = sym.split('@', 1)
+  return (split[0] in args.sym) or (len(split) == 2 and accept_lib(split[1]))
+
 # Run nm to find the undefined symbols, and check whether each is acceptable.
 nm = subprocess.run(['nm', '-uD', '--with-symbol-version', args.binary],
                     stdout=subprocess.PIPE, text=True)
diff --git a/releases.md b/releases.md
index 68c11d0..d466557 100644
--- a/releases.md
+++ b/releases.md
@@ -8,7 +8,8 @@ is being able to cut releases easily whenever we want.
 The releases are just a zip archive containing the `clangd` binary, and the
 clang builtin headers. They should be runnable immediately after extracting the
 archive. The linux binary has `libstdc++` and other dependencies statically
-linked for maximum portability.
+linked for maximum portability, and requires glibc 2.18 (the first version with
+`thread_local` support).
 
 ## Creating a release manually