diff --git a/setup.py b/setup.py
index 292d9305b..84c4db9bb 100755
--- a/setup.py
+++ b/setup.py
@@ -19,8 +19,8 @@ from contextlib import suppress
 from functools import lru_cache, partial
 from pathlib import Path
 from typing import (
-    Callable, Dict, FrozenSet, Iterable, Iterator, List, Optional, Sequence,
-    Set, Tuple, Union
+    Callable, Dict, FrozenSet, Iterable, List, Optional, Sequence, Set, Tuple,
+    Union
 )
 
 from glfw import glfw
@@ -500,20 +500,14 @@ def get_vcs_rev_defines(env: Env, src: str) -> List[str]:
     return ans
 
 
-def get_library_defines(env: Env, src: str) -> Optional[List[str]]:
-    try:
-        return env.library_paths[src]
-    except KeyError:
-        return None
-
-
-SPECIAL_SOURCES: Dict[str, Tuple[str, Union[List[str], Callable[[Env, str], Union[Optional[List[str]], Iterator[str]]]]]] = {
-    'glfw/egl_context.c': ('glfw/egl_context.c', get_library_defines),
-    'kitty/desktop.c': ('kitty/desktop.c', get_library_defines),
-    'kitty/fontconfig.c': ('kitty/fontconfig.c', get_library_defines),
-    'kitty/parser_dump.c': ('kitty/parser.c', ['DUMP_COMMANDS']),
-    'kitty/data-types.c': ('kitty/data-types.c', get_vcs_rev_defines),
-}
+def get_source_specific_defines(env: Env, src: str) -> Tuple[str, Optional[List[str]]]:
+    if src == 'kitty/parser_dump.c':
+        return 'kitty/parser.c', ['DUMP_COMMANDS']
+    if src == 'kitty/data-types.c':
+        return src, get_vcs_rev_defines(env, src)
+    with suppress(KeyError):
+        return src, env.library_paths[src]
+    return src, None
 
 
 def newer(dest: str, *sources: str) -> bool:
@@ -699,13 +693,9 @@ def compile_c_extension(
     for original_src, dest in zip(sources, objects):
         src = original_src
         cppflags = kenv.cppflags[:]
-        is_special = src in SPECIAL_SOURCES
-        if is_special:
-            src, defines_ = SPECIAL_SOURCES[src]
-            defines = defines_(kenv, src) if callable(defines_) else defines_
-            if defines is not None:
-                cppflags.extend(map(define, defines))
-
+        src, defines = get_source_specific_defines(kenv, src)
+        if defines is not None:
+            cppflags.extend(map(define, defines))
         cmd = kenv.cc + ['-MMD'] + cppflags + kenv.cflags
         cmd += ['-c', src] + ['-o', dest]
         key = CompileKey(original_src, os.path.basename(dest))