diff --git a/Makefile b/Makefile
index c86b047..d216841 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,3 @@ build:
 	rm -rf build/*
 	mkdir -p build/dgoods
 	mv dgoods.abi dgoods.wasm build/dgoods/
-
-.PHONY: ddata
-ddata:
-	bash -c "kill $$(pidof nodeos)" && rm -rf ~/.local/share/eosio/nodeos/data/
diff --git a/build/dgoods/dgoods.wasm b/build/dgoods/dgoods.wasm
index 09d3b14..3a67753 100755
Binary files a/build/dgoods/dgoods.wasm and b/build/dgoods/dgoods.wasm differ
diff --git a/include/dasset.hpp b/include/dasset.hpp
index a836e89..482b0f0 100644
--- a/include/dasset.hpp
+++ b/include/dasset.hpp
@@ -27,14 +27,14 @@ namespace dgoods_asset {
 
         void _check_max(const uint64_t& a) {
             static constexpr uint64_t max_amount = ( 1LL << 62 ) - 1;
-            check( a <= max_amount, "max supply must be less than 2^62 - 1");
-            check( a > 0, "max supply must be greater than 0");
+            check( a < max_amount, "max supply must be less than 2^62 - 1");
         }
 
         dasset() {}
 
         void from_string(const string& s) {
             string string_amount = trim(s);
+            check( ( string_amount[0] != '-' ), "Amount can not be negative" );
             auto dot_pos = string_amount.find('.');
             uint64_t uint_part;
             uint64_t frac_part;
@@ -56,6 +56,7 @@ namespace dgoods_asset {
                 frac_part = stoull(string_amount.substr( dot_pos + 1 ));
             }
             amount = uint_part * p10 + frac_part;
+            check( amount > 0, "max supply must be greater than 0");
 
         }
 
@@ -65,6 +66,7 @@ namespace dgoods_asset {
             _check_precision(p);
 
             string string_amount = trim(s);
+            check( ( string_amount[0] != '-' ), "Amount can not be negative" );
             // 1.0 1. 1
             uint64_t uint_part;
             uint64_t frac_part;
@@ -81,6 +83,7 @@ namespace dgoods_asset {
             _check_max(uint_part);
             uint64_t p10 = _get_precision(p);
             amount = uint_part * p10 + frac_part;
+            check( amount > 0, "max supply must be greater than 0");
 
         }
 
diff --git a/include/utility.hpp b/include/utility.hpp
index 2dc00fd..60dfa26 100644
--- a/include/utility.hpp
+++ b/include/utility.hpp
@@ -34,10 +34,12 @@ namespace utility {
 
     tuple<uint64_t, name> parsememo(const string& memo) {
         auto dot_pos = memo.find(',');
+        string errormsg = "malformed memo: must have dgood_id,to_account";
+        check ( dot_pos != string::npos, errormsg.c_str() );
         if ( dot_pos != string::npos ) {
-            check( ( dot_pos != memo.size() - 1 ), "malformed memo, must have dgood_id,to_account");
+            check( ( dot_pos != memo.size() - 1 ), errormsg.c_str() );
         }
-        // need to trim substring
+        // will abort if stoull throws error since wasm no error checking
         uint64_t dgood_id = stoull( trim( memo.substr( 0, dot_pos ) ) );
         name to_account = name( trim ( memo.substr( dot_pos + 1 ) ) );
 
diff --git a/src/dgoods.cpp b/src/dgoods.cpp
index 5062c66..e546985 100644
--- a/src/dgoods.cpp
+++ b/src/dgoods.cpp
@@ -315,12 +315,15 @@ ACTION dgoods::buynft(name from,
                       name to,
                       asset quantity,
                       string memo) {
+    // allow EOS to be sent by sending with empty string memo
+    if ( memo == "deposit" ) return;
+    // don't allow spoofs
     if ( to != get_self() ) return;
     if ( from == name("eosio.stake") ) return;
     if ( quantity.symbol != symbol( symbol_code("EOS"), 4) ) return;
     if ( memo.length() > 32 ) return;
-    // memo format comma separated
-    // dgood_id,to_account
+    //memo format comma separated
+    //dgood_id,to_account
 
     uint64_t dgood_id;
     name to_account;