diff --git a/sources/statistics.F90 b/sources/statistics.F90
index c3e9556..c1f273f 100644
--- a/sources/statistics.F90
+++ b/sources/statistics.F90
@@ -1251,6 +1251,14 @@ module statistics
 !
     gavg(:) = gavg(:) * voli
 
+! calculate pressure for the isothermal case
+!
+    if (ipr <= 0) then
+      gavg(2) = csnd2 * gavg(1)
+      gmin(2) = csnd2 * gmin(1)
+      gmax(2) = csnd2 * gmax(1)
+    end if
+
 ! write down the integrals and statistics to appropriate files
 !
     if (master) then