diff --git a/Tools/peg_generator/pegen/build.py b/Tools/peg_generator/pegen/build.py
index 7df39a3b0ae48e..00295c984d1bb6 100644
--- a/Tools/peg_generator/pegen/build.py
+++ b/Tools/peg_generator/pegen/build.py
@@ -139,6 +139,7 @@ def compile_c_extension(
     ]
     include_dirs = [
         str(MOD_DIR.parent.parent.parent / "Include" / "internal"),
+        str(MOD_DIR.parent.parent.parent / "Include" / "internal" / "mimalloc"),
         str(MOD_DIR.parent.parent.parent / "Parser"),
         str(MOD_DIR.parent.parent.parent / "Parser" / "lexer"),
         str(MOD_DIR.parent.parent.parent / "Parser" / "tokenizer"),