diff --git a/devtimer.py b/devtimer.py
index 24d6f73..d30aeba 100755
--- a/devtimer.py
+++ b/devtimer.py
@@ -5,39 +5,92 @@
 # Permission Hereby Granted For Unrestricted Personal Or Commercial Use
 
 
+from threading import Thread
 from time import time, sleep
 from tm1637 import *
 from wiringpi import wiringPiSetupGpio
 
 wiringPiSetupGpio()
 
+#####
+# Constants
+#####
+
+# Display
+
 BRIGHTNESS = 0x09
 CLK = 21
 DIO = 20
 
+# Compensate for program execution time in master timing loop
+
+CALIBRATION_OFFSET = 0.0032
+
+# Reference temperature in degrees F
+
+NORMAL_TEMP = 68
+
+#####
+# Lookup Table For Compensating Factors
+#####
+
+'''
+  Each paper|film-developer combo has an entry here, expressed as:
+
+    +- correction/degree
+
+  68F is considered "normal".  Temperatures below this will cause the
+  timer to run slower. Temperatures above it, will cause the timer to
+  run faster.  This creates a "virtual second" that reflect time,
+  material, and developer selected.
+
+  WARNING: It takes about 250ms to update the display on a Pi Zero.
+           So, if the "virtual second" falls at or below this, the
+           code will be attempting to do updates faster than the
+           display can handle. So the total amount of compensation
+           cannot be smaller than about 0.300 to be on the safe side.
+'''
+
+compensate = (
+               0.000,     # Normal
+               0.002,     # Small temperature dependency
+               0.004,     # Medium temperature dependency
+               0.010,     # Large temperature dependency
+             )
+
+# Return the current temperature in degrees F
+
+def get_temp():
+    return 72
 
 
-def show_elapsed(tm, elapsed):
+# Update the display with elapsed time
+
+def show_elapsed(display0, elapsed):
+
     min = elapsed // 60
     sec = elapsed % 60
-    d0 = tm.digit_to_segment[min // 10]
-    d1 = tm.digit_to_segment[min % 10]
-    d2 = tm.digit_to_segment[sec // 10]
-    d3 = tm.digit_to_segment[sec % 10]
-    tm.set_segments([d0, 0x80 + d1, d2, d3])
+    d0 = display0.digit_to_segment[min // 10]
+    d1 = display0.digit_to_segment[min % 10]
+    d2 = display0.digit_to_segment[sec // 10]
+    d3 = display0.digit_to_segment[sec % 10]
+    display0.set_segments([d0, 0x80 + d1, d2, d3])
 
-
+# Program entry point
 
 if __name__ == "__main__":
 
-    tm = TM1637(CLK, DIO, BRIGHTNESS)
+    display0 = TM1637(CLK, DIO, BRIGHTNESS)
 
-    start_time = int(time())
-    show_elapsed(tm, 0)
-
+    compensation_profile = 0
+    elapsed_time = 0
     while True:
 
-        sleep(.05)
-        show_elapsed(tm, int(time())-start_time)
-        if int(time())-start_time == 5999:
-            start_time = int(time())
+        last = time()
+        update_thread = Thread(None, show_elapsed, None, (display0, elapsed_time))
+        sleep((1.000 + ((NORMAL_TEMP-get_temp()) * compensate[3])) - CALIBRATION_OFFSET)
+        elapsed_time += 1
+        elapsed_time %= 6000
+        update_thread = Thread(None, show_elapsed, None, (display0, elapsed_time))
+        print(time()-last)
+        update_thread.start()
diff --git a/tm1637.py b/tm1637.py
index e417b5a..bbadd76 100644
--- a/tm1637.py
+++ b/tm1637.py
@@ -1,5 +1,5 @@
 # Tip of the hat to https://github.com/johnlr/raspberrypi-tm1637 for
-# this code.  I has been very slightly modified, but it mostly his
+# this code.  This has been very slightly modified, but it mostly his
 # work.
 
 from time import sleep