diff --git a/libc/lib/CMakeLists.txt b/libc/lib/CMakeLists.txt
--- a/libc/lib/CMakeLists.txt
+++ b/libc/lib/CMakeLists.txt
@@ -26,6 +26,7 @@
     libc.src.string.memcpy
     libc.src.string.strcpy
     libc.src.string.strcat
+    libc.src.string.strlen
 
     # sys/mman.h entrypoints
     libc.src.sys.mman.mmap