diff --git a/.cargo/config.toml b/.cargo/config.toml
index d502ee5..d9defaf 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -3,6 +3,8 @@ target = "avr-specs/avr-atmega328p.json"
 
 [target.'cfg(target_arch = "avr")']
 runner = "ravedude uno -cb 57600"
+# Workaround for: https://github.com/rust-lang/compiler-builtins/issues/420
+rustflags = ["-C", "link-arg=-Wl,--allow-multiple-definition"]
 
 [unstable]
 build-std = ["core"]