diff --git a/contrib/sdk/sources/newlib/libc/Tupfile.lua b/contrib/sdk/sources/newlib/libc/Tupfile.lua
index 9f2c92a347..9e4b52eaf6 100644
--- a/contrib/sdk/sources/newlib/libc/Tupfile.lua
+++ b/contrib/sdk/sources/newlib/libc/Tupfile.lua
@@ -1,6 +1,6 @@
 if tup.getconfig("NO_GCC") ~= "" or tup.getconfig("NO_FASM") ~= "" then return end
 tup.include("../../../../../programs/use_gcc.lua")
-CFLAGS = CFLAGS_OPTIMIZE_SPEED .. " -c -DBUILD_DLL -DMISSING_SYSCALL_NAMES"
+CFLAGS = CFLAGS_OPTIMIZE_SPEED .. " -c -DBUILD_LIBC -DMISSING_SYSCALL_NAMES"
 LDFLAGS = "-shared -s -T libcdll.lds --out-implib $(SDK_DIR)/lib/libc.dll.a --image-base 0"
 -- LDFLAGS = LDFLAGS .. " --output-def libc.orig.def"