diff --git a/README.new b/README.new
index 95399c8ae..c8727ca37 100644
--- a/README.new
+++ b/README.new
@@ -26,3 +26,5 @@ Lmod 7.7+
             caused problems for some users when interacting with TCL.
    (7.7.14) Do not look for lua_json.  Just use the one that comes with Lmod.
             Fix sh_to_modulefile correctly handle bad options (issue #332)
+            Allow pushenv("FOO",false) to clear "FOO" (issue #331)
+            
diff --git a/rt/pushenv/err.txt b/rt/pushenv/err.txt
index 4643eb414..8674a6bdc 100644
--- a/rt/pushenv/err.txt
+++ b/rt/pushenv/err.txt
@@ -2,7 +2,7 @@
 step 1
 lua ProjectDIR/src/lmod.in.lua bash --regression_testing --version
 ===========================
-Modules based on Lua: Version 7.6.12  2017-09-01 18:59 -05:00
+Modules based on Lua: Version 7.7.13  2017-10-31 10:46 -05:00
     by Robert McLay mclay@tacc.utexas.edu
 ===========================
 step 2
@@ -78,11 +78,19 @@ lua ProjectDIR/src/lmod.in.lua bash --regression_testing unload ll/2.0
 ===========================
 ===========================
 step 19
+lua ProjectDIR/src/lmod.in.lua bash --regression_testing load lloyd
+===========================
+===========================
+step 20
+lua ProjectDIR/src/lmod.in.lua bash --regression_testing unload lloyd
+===========================
+===========================
+step 21
 lua ProjectDIR/src/lmod.in.lua bash --regression_testing save
 ===========================
 Saved current collection of modules to: "default"
 ===========================
-step 20
+step 22
 lua ProjectDIR/src/lmod.in.lua bash --regression_testing restore
 ===========================
 Restoring modules from user's default
diff --git a/rt/pushenv/mf/Core/lloyd/1.0.lua b/rt/pushenv/mf/Core/lloyd/1.0.lua
new file mode 100644
index 000000000..9e05d0e2f
--- /dev/null
+++ b/rt/pushenv/mf/Core/lloyd/1.0.lua
@@ -0,0 +1 @@
+pushenv("LLOYD",false)
diff --git a/rt/pushenv/out.txt b/rt/pushenv/out.txt
index f85ed65d2..1b0ef6b8d 100644
--- a/rt/pushenv/out.txt
+++ b/rt/pushenv/out.txt
@@ -348,6 +348,45 @@ __LMOD_STACK_RTM="test";
 export __LMOD_STACK_RTM;
 ===========================
 step 19
+lua ProjectDIR/src/lmod.in.lua bash --regression_testing load lloyd
+===========================
+unset LLOYD;
+__LMOD_REF_COUNT_LOADEDMODULES="intel/13.0:1;mpich/3.0:1;lloyd/1.0:1";
+export __LMOD_REF_COUNT_LOADEDMODULES;
+LOADEDMODULES="intel/13.0:mpich/3.0:lloyd/1.0";
+export LOADEDMODULES;
+MODULEPATH="ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0:ProjectDIR/rt/pushenv/mf/Core";
+export MODULEPATH;
+__LMOD_REF_COUNT__LMFILES_="ProjectDIR/rt/pushenv/mf/Core/intel/13.0.lua:1;ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0/mpich/3.0.lua:1;ProjectDIR/rt/pushenv/mf/Core/lloyd/1.0.lua:1";
+export __LMOD_REF_COUNT__LMFILES_;
+_LMFILES_="ProjectDIR/rt/pushenv/mf/Core/intel/13.0.lua:ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0/mpich/3.0.lua:ProjectDIR/rt/pushenv/mf/Core/lloyd/1.0.lua";
+export _LMFILES_;
+_ModuleTable_='_ModuleTable_={["MTversion"]=3,depthT={},family={},mT={intel={["fn"]="ProjectDIR/rt/pushenv/mf/Core/intel/13.0.lua",["fullName"]="intel/13.0",["loadOrder"]=1,propT={},["stackDepth"]=0,["status"]="active",["userName"]="intel",},lloyd={["fn"]="ProjectDIR/rt/pushenv/mf/Core/lloyd/1.0.lua",["fullName"]="lloyd/1.0",["loadOrder"]=3,propT={},["stackDepth"]=0,["status"]="active",["userName"]="lloyd",},mpich={["fn"]="ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0/mpich/3.0.lua",["fullName"]="mpich/3.0",["loadOrder"]=2,propT={},["stackDepth"]=0,["status"]="active",["userName"]="mpich",},},mpathA={"ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0","ProjectDIR/rt/pushenv/mf/Core",},["systemBaseMPATH"]="ProjectDIR/rt/pushenv/mf/Core",}';
+export _ModuleTable_;
+__LMOD_STACK_LLOYD="false:FOO";
+export __LMOD_STACK_LLOYD;
+===========================
+step 20
+lua ProjectDIR/src/lmod.in.lua bash --regression_testing unload lloyd
+===========================
+LLOYD="FOO";
+export LLOYD;
+__LMOD_REF_COUNT_LOADEDMODULES="intel/13.0:1;mpich/3.0:1";
+export __LMOD_REF_COUNT_LOADEDMODULES;
+LOADEDMODULES="intel/13.0:mpich/3.0";
+export LOADEDMODULES;
+MODULEPATH="ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0:ProjectDIR/rt/pushenv/mf/Core";
+export MODULEPATH;
+__LMOD_REF_COUNT__LMFILES_="ProjectDIR/rt/pushenv/mf/Core/intel/13.0.lua:1;ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0/mpich/3.0.lua:1";
+export __LMOD_REF_COUNT__LMFILES_;
+_LMFILES_="ProjectDIR/rt/pushenv/mf/Core/intel/13.0.lua:ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0/mpich/3.0.lua";
+export _LMFILES_;
+_ModuleTable_='_ModuleTable_={["MTversion"]=3,depthT={},family={},mT={intel={["fn"]="ProjectDIR/rt/pushenv/mf/Core/intel/13.0.lua",["fullName"]="intel/13.0",["loadOrder"]=1,propT={},["stackDepth"]=0,["status"]="active",["userName"]="intel",},mpich={["fn"]="ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0/mpich/3.0.lua",["fullName"]="mpich/3.0",["loadOrder"]=2,propT={},["stackDepth"]=0,["status"]="active",["userName"]="mpich",},},mpathA={"ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0","ProjectDIR/rt/pushenv/mf/Core",},["systemBaseMPATH"]="ProjectDIR/rt/pushenv/mf/Core",}';
+export _ModuleTable_;
+__LMOD_STACK_LLOYD="FOO";
+export __LMOD_STACK_LLOYD;
+===========================
+step 21
 lua ProjectDIR/src/lmod.in.lua bash --regression_testing save
 ===========================
 MODULEPATH="ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0:ProjectDIR/rt/pushenv/mf/Core";
@@ -355,7 +394,7 @@ export MODULEPATH;
 _ModuleTable_='_ModuleTable_={["MTversion"]=3,depthT={},family={},mT={intel={["fn"]="ProjectDIR/rt/pushenv/mf/Core/intel/13.0.lua",["fullName"]="intel/13.0",["loadOrder"]=1,propT={},["stackDepth"]=0,["status"]="active",["userName"]="intel",},mpich={["fn"]="ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0/mpich/3.0.lua",["fullName"]="mpich/3.0",["loadOrder"]=2,propT={},["stackDepth"]=0,["status"]="active",["userName"]="mpich",},},mpathA={"ProjectDIR/rt/pushenv/mf/Compiler/intel/13.0","ProjectDIR/rt/pushenv/mf/Core",},["systemBaseMPATH"]="ProjectDIR/rt/pushenv/mf/Core",}';
 export _ModuleTable_;
 ===========================
-step 20
+step 22
 lua ProjectDIR/src/lmod.in.lua bash --regression_testing restore
 ===========================
 CC="mpicc";
diff --git a/rt/pushenv/pushenv.tdesc b/rt/pushenv/pushenv.tdesc
index 8f63f3bcb..fab54c12e 100644
--- a/rt/pushenv/pushenv.tdesc
+++ b/rt/pushenv/pushenv.tdesc
@@ -45,8 +45,12 @@ testdescript = {
      runLmod load   ll/2.0    #17
      runLmod unload ll/2.0    #18
     
-     runLmod save             #19
-     runLmod restore          #20
+     export LLOYD="FOO"
+     runLmod load   lloyd     #19
+     runLmod unload lloyd     #20
+     
+     runLmod save             #21
+     runLmod restore          #22
 
      HOME_ORIG=$HOME
 
diff --git a/src/MasterControl.lua b/src/MasterControl.lua
index 2cf1cdc14..60de444d7 100644
--- a/src/MasterControl.lua
+++ b/src/MasterControl.lua
@@ -266,9 +266,13 @@ function M.pushenv(self, name, value)
       varT[stackName] = Var:new(stackName, v64, nodups, ":")
    end
 
-
-   v   = tostring(value)
-   v64 = encode64(value)
+   if (value == false) then
+      v   = false
+      v64 = "false"
+   else
+      v   = tostring(value)
+      v64 = encode64(value)
+   end
    local priority = 0
 
    varT[stackName]:prepend(v64, nodups, priority)
@@ -303,7 +307,9 @@ function M.popenv(self, name, value)
 
    local v64 = varT[stackName]:pop()
    local v   = nil
-   if (v64) then
+   if (v64 == "false") then
+      v = false 
+   elseif (v64) then
       v = decode64(v64)
    end
    dbg.print{"v: ", v,"\n"}
diff --git a/src/joinBase64Results b/src/joinBase64Results
index 95b304ad7..835670e67 100755
--- a/src/joinBase64Results
+++ b/src/joinBase64Results
@@ -172,7 +172,7 @@ function joinMT_bash(whole)
             b[#b+1] = name
             b[#b+1] = "=\""
             for v in str:split(":") do
-               v = decode64(v)
+               v = (v ~= "false") and decode64(v) or "false"
                b[#b+1] = v
                b[#b+1] = ":"
             end
@@ -209,7 +209,7 @@ function joinMT_csh(whole)
             b[#b+1] = name
             b[#b+1] = " \""
             for v in str:split(":") do
-               v = decode64(v)
+               v = (v ~= "false") and decode64(v) or "false"
                b[#b+1] = v
                b[#b+1] = ":"
             end