diff --git a/PARAM/hdc.param b/PARAM/hdc.param
index cfefa9ab499d8a3d28f81b3b7045c3dd60c51b8f..7d34481335ddce44c22d437cf7cc51b1e80abfb8 100644
--- a/PARAM/hdc.param
+++ b/PARAM/hdc.param
@@ -20,7 +20,7 @@
   hdc_tdc_max_win = 5500,5000,5500,5500,5000,5500
                     5500,5000,5500,5500,5000,5500
 ; hms drift chamber tdc's time per channel
-        hdc_tdc_time_per_channel = 0.10
+        hdc_tdc_time_per_channel = -0.10
 ; hms zero time for drift chambers	!DECREASING this number moves the hdtime plots to LOWER time.
    hdc_plane_time_zero = -213.0,-213.0,-213.0,-213.0,-213.0,-213.0
   		        -213.0,-213.0,-213.0,-213.0,-213.0,-213.0