diff --git a/src/pifmrds/control_pipe.h b/src/pifmrds/control_pipe.h
index 4f0562b..1421e82 100644
--- a/src/pifmrds/control_pipe.h
+++ b/src/pifmrds/control_pipe.h
@@ -17,7 +17,7 @@
 
 typedef struct {
     int res;
-    char arg[70];
+    char *arg;
 } ResultAndArg;
 
 extern int open_control_pipe(char *filename, volatile uint32_t *padreg);