diff --git a/tcl/Sdc.tcl b/tcl/Sdc.tcl
index 6bfa8cc4..0bbe9761 100644
--- a/tcl/Sdc.tcl
+++ b/tcl/Sdc.tcl
@@ -2448,8 +2448,8 @@ define_cmd_args "set_input_transition" \
   {[-rise] [-fall] [-min] [-max] transition ports}
 
 proc set_input_transition { args } {
-  parse_key_args "set_input_transition" args keys {-clock -clock_fall} \
-    flags {-rise -fall -max -min}
+  parse_key_args "set_input_transition" args keys {-clock} \
+    flags {-rise -fall -max -min -clock_fall}
   
   set tr [parse_rise_fall_flags flags]
   set min_max [parse_min_max_all_flags flags]
@@ -2465,7 +2465,7 @@ proc set_input_transition { args } {
   if [info exists keys(-clock)] {
     sta_warn 361 "-clock not supported."
   }
-  if [info exists keys(-clock_fall)] {
+  if [info exists flags(-clock_fall)] {
     sta_warn 362 "-clock_fall not supported."
   }