diff --git a/libc/arch-arm/arm.mk b/libc/arch-arm/arm.mk
index 7c423ab..260d72e 100644
--- a/libc/arch-arm/arm.mk
+++ b/libc/arch-arm/arm.mk
@@ -5,6 +5,7 @@
     bionic/legacy_32_bit_support.cpp \
     bionic/ndk_cruft.cpp \
     bionic/time64.c \
+    upstream-openbsd/lib/libc/stdio/putw.c \
 
 # These are shared by all the 32-bit targets, but not the 64-bit ones.
 libc_bionic_src_files_arm := \