diff --git a/litex/soc/software/libc/stdio.c b/litex/soc/software/libc/stdio.c
index fb558a3ed..bab8d1d99 100644
--- a/litex/soc/software/libc/stdio.c
+++ b/litex/soc/software/libc/stdio.c
@@ -33,6 +33,7 @@ litex_getc(FILE *file)
 			return uart_read();
 #endif
 	}
+	return -1;
 }
 
 static FILE __stdio = FDEV_SETUP_STREAM(litex_putc, litex_getc, NULL, _FDEV_SETUP_RW);