diff --git a/grbl/probe.c b/grbl/probe.c
index 985d5872..09996a88 100644
--- a/grbl/probe.c
+++ b/grbl/probe.c
@@ -22,7 +22,7 @@
 
 
 // Inverts the probe pin state depending on user settings and probing cycle mode.
-uint8_t probe_invert_mask;
+uint16_t probe_invert_mask;
 
 
 // Probe pin initialization routine.