diff --git a/llvm/PKGBUILD b/llvm/PKGBUILD
index e9401c29..9ed173da 100644
--- a/llvm/PKGBUILD
+++ b/llvm/PKGBUILD
@@ -186,9 +186,9 @@ build() {
   platform_config+=(-DLLVM_TARGETS_TO_BUILD="AArch64;X86")
 
   # Unlike Linux, Cygwin does not define it OOTB
-  export CFLAGS=-D_GNU_SOURCE=1
-  export CXXFLAGS=-D_GNU_SOURCE=1
-  export CPPFLAGS=-D_GNU_SOURCE=1
+  CFLAGS+=" -D_GNU_SOURCE=1"
+  CXXFLAGS+=" -D_GNU_SOURCE=1"
+  CPPFLAGS+=" -D_GNU_SOURCE=1"
 
   cmake \
     -GNinja \