diff --git a/digital-inputs/firmware/Makefile b/digital-inputs/firmware/Makefile
index a998f73..3e70945 100644
--- a/digital-inputs/firmware/Makefile
+++ b/digital-inputs/firmware/Makefile
@@ -162,7 +162,7 @@ CPPWARN = -Wall -Wextra -Wundef
 #
 
 # List all user C define here, like -D_DEBUG=1
-UDEFS =
+UDEFS = -DCHPRINTF_USE_FLOAT=1
 
 # Define ASM defines here
 UADEFS =