diff --git a/phreeqc3-doc/RELEASE.TXT b/phreeqc3-doc/RELEASE.TXT
index 63ccddc2..759671df 100644
--- a/phreeqc3-doc/RELEASE.TXT
+++ b/phreeqc3-doc/RELEASE.TXT
@@ -1,5 +1,13 @@
 Version @PHREEQC_VER@: @PHREEQC_DATE@
 
+  	--------------
+	July 30, 2021
+	--------------
+	PHREEQC: Modified the numerical method for Pitzer calculations when using
+	Peng-Robinson  gases. The calculation of numerical derivatives was 
+	modified to account for the sequence of calculations, particularly that
+	the mole fractions of gases are calculated within the molalities method. 
+
   	-------------
 	June 14, 2021
 	-------------