diff --git a/sw/buildroot_overlay/etc/init.d/S90program_fpga.sh b/sw/buildroot_overlay/etc/init.d/S90program_fpga.sh
index 34aec21..02ac8e2 100755
--- a/sw/buildroot_overlay/etc/init.d/S90program_fpga.sh
+++ b/sw/buildroot_overlay/etc/init.d/S90program_fpga.sh
@@ -44,8 +44,8 @@ start() {
         exit 1
     fi
 
-    # Drive internal GPIO line 0 low to reset FPGA.
-    # Note: EMIO GPIO line n is gpio (n + 54) in Linux.
+    # Drive internal GPIO(0) low to reset FPGA.
+    # Note: EMIO GPIO(n) is gpio (n + 54) in Linux.
     gpioset 0 54=0
 
     # Program FPGA.
@@ -57,14 +57,20 @@ start() {
     sleep 5
 
     if [ "$eeprom_hw_rev" = "STEM_125-14_v1.0" ]; then
-        # Drive internal GPIO line 2 high to enable ADC duty cycle stabilizer.
+        # Drive internal GPIO(2) high to enable ADC duty cycle stabilizer.
         gpioset 0 56=1
     elif [ "$eeprom_hw_rev" = "STEM_125-14_Z7020_4IN_v1.3" ]; then
         # Program ADCs for DDR data mode and enable duty cycle stabilizer.
         /opt/puzzlefw/bin/puzzle-adccfg init --force --dcs
+
+        # Enable ADC output randomization.
+        /opt/puzzlefw/bin/puzzle-adccfg format --rand
+
+        # Drive internal GPIO(3) high to enable sample derandomization in FPGA.
+        gpioset 0 57=1
     fi
 
-    # Drive internal GPIO line 0 high to release FPGA reset.
+    # Drive internal GPIO(0) high to release FPGA reset.
     gpioset 0 54=1
     sleep 1
 }