diff --git a/site_ansto/instrument/util/gen_sct.py b/site_ansto/instrument/util/gen_sct.py
index 275b9df1..7332b890 100755
--- a/site_ansto/instrument/util/gen_sct.py
+++ b/site_ansto/instrument/util/gen_sct.py
@@ -971,7 +971,7 @@ def put_read_function(MyDriver, func):
     txt += ['      sct oldval ${data}']
     txt += ['      sct update ${data}']
     txt += ['      sct utime readtime']
-    txt += ['      }']
+    txt += ['    }']
     txt += ['    return ${nextState}']
     txt += ['  } catch_message ]']
     txt += ['  handle_exception ${catch_status} ${catch_message}']
@@ -1115,19 +1115,19 @@ def put_pid_function(MyDriver, func):
     txt += ['proc %s::%s {tc_root sp pv} {' % (MyDriver['namespace'], func)]
     txt += ['  set catch_status [ catch {']
     txt += ['    debug_log ${tc_root} 1 "%s tc_root=${tc_root} sct=[sct] pv=${pv} sp=${sp}"' % func]
-    txt += ['    sct pid_error [expr ${sp} - ${pv}]']
-    txt += ['    set p_value [expr [sct pid_pvalue] * [sct pid_error]]']
-    txt += ['    set d_value [expr [sct pid_dvalue] * (${pv} - [sct oldval])]']
+    txt += ['    sct pid_error [expr {${sp} - ${pv}}]']
+    txt += ['    set p_value [expr {[sct pid_pvalue] * [sct pid_error]}]']
+    txt += ['    set d_value [expr {[sct pid_dvalue] * (${pv} - [sct oldval])}]']
     txt += ['    sct pid_deriv [sct pid_error]']
-    txt += ['    sct pid_integ [expr [sct pid_integ] + [sct pid_error]]']
+    txt += ['    sct pid_integ [expr {[sct pid_integ] + [sct pid_error]}]']
     txt += ['    if { [sct pid_integ] > [sct pid_imax] } {']
     txt += ['      sct pid_integ [sct pid_imax]']
     txt += ['    }']
     txt += ['    if { [sct pid_integ] < -[sct pid_imax] } {']
     txt += ['      sct pid_integ -[sct pid_imax]']
     txt += ['    }']
-    txt += ['    set i_value [expr [sct pid_ivalue] * [sct pid_integ]]']
-    txt += ['    set pid [expr ${p_value} + ${i_value} + ${d_value}]']
+    txt += ['    set i_value [expr {[sct pid_ivalue] * [sct pid_integ]}]']
+    txt += ['    set pid [expr {${p_value} + ${i_value} + ${d_value}}]']
     if func in MyDriver['Funcs'] and len(MyDriver['Funcs'][func]['text']) > 0:
         txt += ['# %s hook code starts' % func]
         txt += MyDriver['Funcs'][func]['text']