diff --git a/PENDING.md b/PENDING.md
index 1c17731e2b7c..a0985593e838 100644
--- a/PENDING.md
+++ b/PENDING.md
@@ -62,7 +62,8 @@ IMPROVEMENTS
 
 * SDK
  - [x/mock/simulation] [\#2720] major cleanup, introduction of helper objects, reorganization
- - \#2821 Codespaces are now strings
+ - #2815 Gas unit fields changed from `int64` to `uint64`.
+ - #2821 Codespaces are now strings
 
 * Tendermint
  - #2796 Update to go-amino 0.14.1
diff --git a/baseapp/baseapp.go b/baseapp/baseapp.go
index 0d557102414b..34f9d817dec8 100644
--- a/baseapp/baseapp.go
+++ b/baseapp/baseapp.go
@@ -451,8 +451,8 @@ func (app *BaseApp) CheckTx(txBytes []byte) (res abci.ResponseCheckTx) {
 		Code:      uint32(result.Code),
 		Data:      result.Data,
 		Log:       result.Log,
-		GasWanted: result.GasWanted,
-		GasUsed:   result.GasUsed,
+		GasWanted: int64(result.GasWanted), // TODO: Should type accept unsigned ints?
+		GasUsed:   int64(result.GasUsed),   // TODO: Should type accept unsigned ints?
 		Tags:      result.Tags,
 	}
 }
@@ -477,8 +477,8 @@ func (app *BaseApp) DeliverTx(txBytes []byte) (res abci.ResponseDeliverTx) {
 		Codespace: string(result.Codespace),
 		Data:      result.Data,
 		Log:       result.Log,
-		GasWanted: result.GasWanted,
-		GasUsed:   result.GasUsed,
+		GasWanted: int64(result.GasWanted), // TODO: Should type accept unsigned ints?
+		GasUsed:   int64(result.GasUsed),   // TODO: Should type accept unsigned ints?
 		Tags:      result.Tags,
 	}
 }
@@ -614,7 +614,7 @@ func (app *BaseApp) runTx(mode runTxMode, txBytes []byte, tx sdk.Tx) (result sdk
 	// NOTE: GasWanted should be returned by the AnteHandler. GasUsed is
 	// determined by the GasMeter. We need access to the context to get the gas
 	// meter so we initialize upfront.
-	var gasWanted int64
+	var gasWanted uint64
 
 	ctx := app.getContextForAnte(mode, txBytes)
 	ctx = app.initializeContext(ctx, mode)
diff --git a/baseapp/baseapp_test.go b/baseapp/baseapp_test.go
index 9c2e7e1a0da7..ba3830e920ad 100644
--- a/baseapp/baseapp_test.go
+++ b/baseapp/baseapp_test.go
@@ -618,7 +618,7 @@ func TestConcurrentCheckDeliver(t *testing.T) {
 // Simulate() and Query("/app/simulate", txBytes) should give
 // the same results.
 func TestSimulateTx(t *testing.T) {
-	gasConsumed := int64(5)
+	gasConsumed := uint64(5)
 
 	anteOpt := func(bapp *BaseApp) {
 		bapp.SetAnteHandler(func(ctx sdk.Context, tx sdk.Tx, simulate bool) (newCtx sdk.Context, res sdk.Result, abort bool) {
@@ -765,7 +765,7 @@ func TestRunInvalidTransaction(t *testing.T) {
 
 // Test that transactions exceeding gas limits fail
 func TestTxGasLimits(t *testing.T) {
-	gasGranted := int64(10)
+	gasGranted := uint64(10)
 	anteOpt := func(bapp *BaseApp) {
 		bapp.SetAnteHandler(func(ctx sdk.Context, tx sdk.Tx, simulate bool) (newCtx sdk.Context, res sdk.Result, abort bool) {
 			newCtx = ctx.WithGasMeter(sdk.NewGasMeter(gasGranted))
@@ -790,7 +790,7 @@ func TestTxGasLimits(t *testing.T) {
 			}()
 
 			count := tx.(*txTest).Counter
-			newCtx.GasMeter().ConsumeGas(count, "counter-ante")
+			newCtx.GasMeter().ConsumeGas(uint64(count), "counter-ante")
 			res = sdk.Result{
 				GasWanted: gasGranted,
 			}
@@ -802,7 +802,7 @@ func TestTxGasLimits(t *testing.T) {
 	routerOpt := func(bapp *BaseApp) {
 		bapp.Router().AddRoute(routeMsgCounter, func(ctx sdk.Context, msg sdk.Msg) sdk.Result {
 			count := msg.(msgCounter).Counter
-			ctx.GasMeter().ConsumeGas(count, "counter-handler")
+			ctx.GasMeter().ConsumeGas(uint64(count), "counter-handler")
 			return sdk.Result{}
 		})
 	}
@@ -813,7 +813,7 @@ func TestTxGasLimits(t *testing.T) {
 
 	testCases := []struct {
 		tx      *txTest
-		gasUsed int64
+		gasUsed uint64
 		fail    bool
 	}{
 		{newTxCounter(0, 0), 0, false},
diff --git a/client/flags.go b/client/flags.go
index dfadab07e43f..ffb2a0c2f04f 100644
--- a/client/flags.go
+++ b/client/flags.go
@@ -124,7 +124,7 @@ func RegisterRestServerFlags(cmd *cobra.Command) *cobra.Command {
 // GasSetting encapsulates the possible values passed through the --gas flag.
 type GasSetting struct {
 	Simulate bool
-	Gas      int64
+	Gas      uint64
 }
 
 // Type returns the flag's value type.
@@ -140,18 +140,18 @@ func (v *GasSetting) String() string {
 	if v.Simulate {
 		return GasFlagSimulate
 	}
-	return strconv.FormatInt(v.Gas, 10)
+	return strconv.FormatUint(v.Gas, 10)
 }
 
 // ParseGasFlag parses the value of the --gas flag.
-func ReadGasFlag(s string) (simulate bool, gas int64, err error) {
+func ReadGasFlag(s string) (simulate bool, gas uint64, err error) {
 	switch s {
 	case "":
 		gas = DefaultGasLimit
 	case GasFlagSimulate:
 		simulate = true
 	default:
-		gas, err = strconv.ParseInt(s, 10, 64)
+		gas, err = strconv.ParseUint(s, 10, 64)
 		if err != nil {
 			err = fmt.Errorf("gas must be either integer or %q", GasFlagSimulate)
 			return
diff --git a/client/lcd/lcd_test.go b/client/lcd/lcd_test.go
index 1be908e98bdb..885e4b914f7c 100644
--- a/client/lcd/lcd_test.go
+++ b/client/lcd/lcd_test.go
@@ -283,7 +283,7 @@ func TestCoinSend(t *testing.T) {
 
 	// test failure with negative gas
 	res, body, _ = doSendWithGas(t, port, seed, name, password, addr, "-200", 0, "")
-	require.Equal(t, http.StatusInternalServerError, res.StatusCode, body)
+	require.Equal(t, http.StatusBadRequest, res.StatusCode, body)
 
 	// test failure with 0 gas
 	res, body, _ = doSendWithGas(t, port, seed, name, password, addr, "0", 0, "")
@@ -389,8 +389,8 @@ func TestCoinSendGenerateSignAndBroadcast(t *testing.T) {
 	require.Nil(t, cdc.UnmarshalJSON([]byte(body), &resultTx))
 	require.Equal(t, uint32(0), resultTx.CheckTx.Code)
 	require.Equal(t, uint32(0), resultTx.DeliverTx.Code)
-	require.Equal(t, gasEstimate, resultTx.DeliverTx.GasWanted)
-	require.Equal(t, gasEstimate, resultTx.DeliverTx.GasUsed)
+	require.Equal(t, gasEstimate, uint64(resultTx.DeliverTx.GasWanted))
+	require.Equal(t, gasEstimate, uint64(resultTx.DeliverTx.GasUsed))
 }
 
 func TestTxs(t *testing.T) {
diff --git a/client/utils/rest.go b/client/utils/rest.go
index 53c6186921db..13347098b39e 100644
--- a/client/utils/rest.go
+++ b/client/utils/rest.go
@@ -34,7 +34,7 @@ func WriteErrorResponse(w http.ResponseWriter, status int, err string) {
 
 // WriteSimulationResponse prepares and writes an HTTP
 // response for transactions simulations.
-func WriteSimulationResponse(w http.ResponseWriter, gas int64) {
+func WriteSimulationResponse(w http.ResponseWriter, gas uint64) {
 	w.WriteHeader(http.StatusOK)
 	w.Write([]byte(fmt.Sprintf(`{"gas_estimate":%v}`, gas)))
 }
diff --git a/client/utils/utils.go b/client/utils/utils.go
index fee7c7fe2557..46bb9799c1c2 100644
--- a/client/utils/utils.go
+++ b/client/utils/utils.go
@@ -71,7 +71,7 @@ func EnrichCtxWithGas(txBldr authtxb.TxBuilder, cliCtx context.CLIContext, name
 
 // CalculateGas simulates the execution of a transaction and returns
 // both the estimate obtained by the query and the adjusted amount.
-func CalculateGas(queryFunc func(string, common.HexBytes) ([]byte, error), cdc *amino.Codec, txBytes []byte, adjustment float64) (estimate, adjusted int64, err error) {
+func CalculateGas(queryFunc func(string, common.HexBytes) ([]byte, error), cdc *amino.Codec, txBytes []byte, adjustment float64) (estimate, adjusted uint64, err error) {
 	// run a simulation (via /app/simulate query) to
 	// estimate gas and update TxBuilder accordingly
 	rawRes, err := queryFunc("/app/simulate", txBytes)
@@ -152,7 +152,7 @@ func SignStdTx(txBldr authtxb.TxBuilder, cliCtx context.CLIContext, name string,
 
 // nolint
 // SimulateMsgs simulates the transaction and returns the gas estimate and the adjusted value.
-func simulateMsgs(txBldr authtxb.TxBuilder, cliCtx context.CLIContext, name string, msgs []sdk.Msg) (estimated, adjusted int64, err error) {
+func simulateMsgs(txBldr authtxb.TxBuilder, cliCtx context.CLIContext, name string, msgs []sdk.Msg) (estimated, adjusted uint64, err error) {
 	txBytes, err := txBldr.BuildWithPubKey(name, msgs)
 	if err != nil {
 		return
@@ -161,11 +161,11 @@ func simulateMsgs(txBldr authtxb.TxBuilder, cliCtx context.CLIContext, name stri
 	return
 }
 
-func adjustGasEstimate(estimate int64, adjustment float64) int64 {
-	return int64(adjustment * float64(estimate))
+func adjustGasEstimate(estimate uint64, adjustment float64) uint64 {
+	return uint64(adjustment * float64(estimate))
 }
 
-func parseQueryResponse(cdc *amino.Codec, rawRes []byte) (int64, error) {
+func parseQueryResponse(cdc *amino.Codec, rawRes []byte) (uint64, error) {
 	var simulationResult sdk.Result
 	if err := cdc.UnmarshalBinaryLengthPrefixed(rawRes, &simulationResult); err != nil {
 		return 0, err
diff --git a/client/utils/utils_test.go b/client/utils/utils_test.go
index c3bf315699ac..b22a50806cc8 100644
--- a/client/utils/utils_test.go
+++ b/client/utils/utils_test.go
@@ -14,16 +14,16 @@ func TestParseQueryResponse(t *testing.T) {
 	cdc := app.MakeCodec()
 	sdkResBytes := cdc.MustMarshalBinaryLengthPrefixed(sdk.Result{GasUsed: 10})
 	gas, err := parseQueryResponse(cdc, sdkResBytes)
-	assert.Equal(t, gas, int64(10))
+	assert.Equal(t, gas, uint64(10))
 	assert.Nil(t, err)
 	gas, err = parseQueryResponse(cdc, []byte("fuzzy"))
-	assert.Equal(t, gas, int64(0))
+	assert.Equal(t, gas, uint64(0))
 	assert.NotNil(t, err)
 }
 
 func TestCalculateGas(t *testing.T) {
 	cdc := app.MakeCodec()
-	makeQueryFunc := func(gasUsed int64, wantErr bool) func(string, common.HexBytes) ([]byte, error) {
+	makeQueryFunc := func(gasUsed uint64, wantErr bool) func(string, common.HexBytes) ([]byte, error) {
 		return func(string, common.HexBytes) ([]byte, error) {
 			if wantErr {
 				return nil, errors.New("")
@@ -32,15 +32,15 @@ func TestCalculateGas(t *testing.T) {
 		}
 	}
 	type args struct {
-		queryFuncGasUsed int64
+		queryFuncGasUsed uint64
 		queryFuncWantErr bool
 		adjustment       float64
 	}
 	tests := []struct {
 		name         string
 		args         args
-		wantEstimate int64
-		wantAdjusted int64
+		wantEstimate uint64
+		wantAdjusted uint64
 		wantErr      bool
 	}{
 		{"error", args{0, true, 1.2}, 0, 0, true},
diff --git a/cmd/gaia/app/genesis.go b/cmd/gaia/app/genesis.go
index 7d95bbfa7d51..5ce9ab8b95e0 100644
--- a/cmd/gaia/app/genesis.go
+++ b/cmd/gaia/app/genesis.go
@@ -91,7 +91,6 @@ func (ga *GenesisAccount) ToAccount() (acc *auth.BaseAccount) {
 	}
 }
 
-
 // Create the core parameters for genesis initialization for gaia
 // note that the pubkey input is this machines pubkey
 func GaiaAppGenState(cdc *codec.Codec, genDoc tmtypes.GenesisDoc, appGenTxs []json.RawMessage) (
@@ -279,7 +278,7 @@ func CollectStdTxs(cdc *codec.Codec, moniker string, genTxsDir string, genDoc tm
 
 func NewDefaultGenesisAccount(addr sdk.AccAddress) GenesisAccount {
 	accAuth := auth.NewBaseAccountWithAddress(addr)
-	coins :=sdk.Coins{
+	coins := sdk.Coins{
 		{"fooToken", sdk.NewInt(1000)},
 		{bondDenom, freeFermionsAcc},
 	}
diff --git a/cmd/gaia/cli_test/cli_test.go b/cmd/gaia/cli_test/cli_test.go
index 62f4d0d64f04..26e6fcaa3673 100644
--- a/cmd/gaia/cli_test/cli_test.go
+++ b/cmd/gaia/cli_test/cli_test.go
@@ -475,7 +475,7 @@ func TestGaiaCLISendGenerateSignAndBroadcast(t *testing.T) {
 	require.True(t, success)
 	require.Empty(t, stderr)
 	msg := unmarshalStdTx(t, stdout)
-	require.Equal(t, msg.Fee.Gas, int64(client.DefaultGasLimit))
+	require.Equal(t, msg.Fee.Gas, uint64(client.DefaultGasLimit))
 	require.Equal(t, len(msg.Msgs), 1)
 	require.Equal(t, 0, len(msg.GetSignatures()))
 
@@ -486,7 +486,7 @@ func TestGaiaCLISendGenerateSignAndBroadcast(t *testing.T) {
 	require.True(t, success)
 	require.Empty(t, stderr)
 	msg = unmarshalStdTx(t, stdout)
-	require.Equal(t, msg.Fee.Gas, int64(100))
+	require.Equal(t, msg.Fee.Gas, uint64(100))
 	require.Equal(t, len(msg.Msgs), 1)
 	require.Equal(t, 0, len(msg.GetSignatures()))
 
@@ -543,9 +543,8 @@ func TestGaiaCLISendGenerateSignAndBroadcast(t *testing.T) {
 	}
 
 	require.Nil(t, app.MakeCodec().UnmarshalJSON([]byte(stdout), &result))
-	require.Equal(t, msg.Fee.Gas, result.Response.GasUsed)
-	require.Equal(t, msg.Fee.Gas, result.Response.GasWanted)
-
+	require.Equal(t, msg.Fee.Gas, uint64(result.Response.GasUsed))
+	require.Equal(t, msg.Fee.Gas, uint64(result.Response.GasWanted))
 	tests.WaitForNextNBlocksTM(2, port)
 
 	barAcc := executeGetAccount(t, fmt.Sprintf("gaiacli query account %s %v", barAddr, flags))
diff --git a/cmd/gaia/init/genesis_accts_test.go b/cmd/gaia/init/genesis_accts_test.go
index 8825a8cd3483..49634a90c4c4 100644
--- a/cmd/gaia/init/genesis_accts_test.go
+++ b/cmd/gaia/init/genesis_accts_test.go
@@ -25,14 +25,14 @@ func TestAddGenesisAccount(t *testing.T) {
 	}{
 		{
 			"valid account",
-		args{
-			app.GenesisState{},
-			addr1,
-			sdk.Coins{},
-		},
-		false},
+			args{
+				app.GenesisState{},
+				addr1,
+				sdk.Coins{},
+			},
+			false},
 		{"dup account", args{
-			app.GenesisState{Accounts: []app.GenesisAccount{app.GenesisAccount{Address:addr1}}},
+			app.GenesisState{Accounts: []app.GenesisAccount{{Address: addr1}}},
 			addr1,
 			sdk.Coins{}}, true},
 	}
diff --git a/docs/examples/democoin/cmd/democoind/main.go b/docs/examples/democoin/cmd/democoind/main.go
index 29e2640fde31..730109798c16 100644
--- a/docs/examples/democoin/cmd/democoind/main.go
+++ b/docs/examples/democoin/cmd/democoind/main.go
@@ -30,7 +30,6 @@ const (
 	flagClientHome = "home-client"
 )
 
-
 // coolGenAppParams sets up the app_state and appends the cool app state
 func CoolAppGenState(cdc *codec.Codec, genDoc tmtypes.GenesisDoc, appGenTxs []json.RawMessage) (
 	appState json.RawMessage, err error) {
diff --git a/server/init.go b/server/init.go
index 3a6c6adae599..e1655c27ea68 100644
--- a/server/init.go
+++ b/server/init.go
@@ -15,7 +15,6 @@ import (
 	tmtypes "github.com/tendermint/tendermint/types"
 )
 
-
 // SimpleGenTx is a simple genesis tx
 type SimpleGenTx struct {
 	Addr sdk.AccAddress `json:"addr"`
@@ -23,7 +22,6 @@ type SimpleGenTx struct {
 
 //_____________________________________________________________________
 
-
 // Generate a genesis transaction
 func SimpleAppGenTx(cdc *codec.Codec, pk crypto.PubKey) (
 	appGenTx, cliPrint json.RawMessage, validator types.GenesisValidator, err error) {
diff --git a/store/gaskvstore_test.go b/store/gaskvstore_test.go
index ba77bae1f889..69f4ae204e4d 100644
--- a/store/gaskvstore_test.go
+++ b/store/gaskvstore_test.go
@@ -73,15 +73,15 @@ func testGasKVStoreWrap(t *testing.T, store KVStore) {
 	meter := sdk.NewGasMeter(10000)
 
 	store = store.Gas(meter, sdk.GasConfig{HasCost: 10})
-	require.Equal(t, int64(0), meter.GasConsumed())
+	require.Equal(t, uint64(0), meter.GasConsumed())
 
 	store.Has([]byte("key"))
-	require.Equal(t, int64(10), meter.GasConsumed())
+	require.Equal(t, uint64(10), meter.GasConsumed())
 
 	store = store.Gas(meter, sdk.GasConfig{HasCost: 20})
 
 	store.Has([]byte("key"))
-	require.Equal(t, int64(40), meter.GasConsumed())
+	require.Equal(t, uint64(40), meter.GasConsumed())
 }
 
 func TestGasKVStoreWrap(t *testing.T) {
diff --git a/types/context.go b/types/context.go
index bfb4c58fed10..267e66681528 100644
--- a/types/context.go
+++ b/types/context.go
@@ -203,8 +203,10 @@ func (c Context) WithConsensusParams(params *abci.ConsensusParams) Context {
 	if params == nil {
 		return c
 	}
+
+	// TODO: Do we need to handle invalid MaxGas values?
 	return c.withValue(contextKeyConsensusParams, params).
-		WithGasMeter(NewGasMeter(params.BlockSize.MaxGas))
+		WithGasMeter(NewGasMeter(uint64(params.BlockSize.MaxGas)))
 }
 
 func (c Context) WithChainID(chainID string) Context { return c.withValue(contextKeyChainID, chainID) }
diff --git a/types/gas.go b/types/gas.go
index 7b034746703b..656bd1d04c97 100644
--- a/types/gas.go
+++ b/types/gas.go
@@ -18,13 +18,19 @@ var (
 )
 
 // Gas measured by the SDK
-type Gas = int64
+type Gas = uint64
 
 // ErrorOutOfGas defines an error thrown when an action results in out of gas.
 type ErrorOutOfGas struct {
 	Descriptor string
 }
 
+// ErrorGasOverflow defines an error thrown when an action results gas consumption
+// unsigned integer overflow.
+type ErrorGasOverflow struct {
+	Descriptor string
+}
+
 // GasMeter interface to track gas consumption
 type GasMeter interface {
 	GasConsumed() Gas
@@ -49,7 +55,14 @@ func (g *basicGasMeter) GasConsumed() Gas {
 }
 
 func (g *basicGasMeter) ConsumeGas(amount Gas, descriptor string) {
-	g.consumed += amount
+	var overflow bool
+
+	// TODO: Should we set the consumed field after overflow checking?
+	g.consumed, overflow = AddUint64Overflow(g.consumed, amount)
+	if overflow {
+		panic(ErrorGasOverflow{descriptor})
+	}
+
 	if g.consumed > g.limit {
 		panic(ErrorOutOfGas{descriptor})
 	}
@@ -71,7 +84,13 @@ func (g *infiniteGasMeter) GasConsumed() Gas {
 }
 
 func (g *infiniteGasMeter) ConsumeGas(amount Gas, descriptor string) {
-	g.consumed += amount
+	var overflow bool
+
+	// TODO: Should we set the consumed field after overflow checking?
+	g.consumed, overflow = AddUint64Overflow(g.consumed, amount)
+	if overflow {
+		panic(ErrorGasOverflow{descriptor})
+	}
 }
 
 // GasConfig defines gas cost for each operation on KVStores
diff --git a/types/gas_test.go b/types/gas_test.go
index cd2384d12d39..f4452053fbd0 100644
--- a/types/gas_test.go
+++ b/types/gas_test.go
@@ -21,7 +21,7 @@ func TestGasMeter(t *testing.T) {
 
 	for tcnum, tc := range cases {
 		meter := NewGasMeter(tc.limit)
-		used := int64(0)
+		used := uint64(0)
 
 		for unum, usage := range tc.usage {
 			used += usage
diff --git a/types/int.go b/types/int.go
index c2bef7a64fcb..2083168e9cfd 100644
--- a/types/int.go
+++ b/types/int.go
@@ -2,6 +2,7 @@ package types
 
 import (
 	"encoding/json"
+	"math"
 	"testing"
 
 	"math/big"
@@ -529,6 +530,16 @@ func (i *Uint) UnmarshalJSON(bz []byte) error {
 
 //__________________________________________________________________________
 
+// AddUint64Overflow performs the addition operation on two uint64 integers and
+// returns a boolean on whether or not the result overflows.
+func AddUint64Overflow(a, b uint64) (uint64, bool) {
+	if math.MaxUint64-a < b {
+		return 0, true
+	}
+
+	return a + b, false
+}
+
 // intended to be used with require/assert:  require.True(IntEq(...))
 func IntEq(t *testing.T, exp, got Int) (*testing.T, bool, string, string, string) {
 	return t, exp.Equal(got), "expected:\t%v\ngot:\t\t%v", exp.String(), got.String()
diff --git a/types/int_test.go b/types/int_test.go
index cd357c4f77ac..78bee66bfaa0 100644
--- a/types/int_test.go
+++ b/types/int_test.go
@@ -590,3 +590,28 @@ func TestEncodingTableUint(t *testing.T) {
 		require.Equal(t, tc.i, i, "Unmarshaled value is different from expected. tc #%d", tcnum)
 	}
 }
+
+func TestAddUint64Overflow(t *testing.T) {
+	testCases := []struct {
+		a, b     uint64
+		result   uint64
+		overflow bool
+	}{
+		{0, 0, 0, false},
+		{100, 100, 200, false},
+		{math.MaxUint64 / 2, math.MaxUint64/2 + 1, math.MaxUint64, false},
+		{math.MaxUint64 / 2, math.MaxUint64/2 + 2, 0, true},
+	}
+
+	for i, tc := range testCases {
+		res, overflow := AddUint64Overflow(tc.a, tc.b)
+		require.Equal(
+			t, tc.overflow, overflow,
+			"invalid overflow result; tc: #%d, a: %d, b: %d", i, tc.a, tc.b,
+		)
+		require.Equal(
+			t, tc.result, res,
+			"invalid uint64 result; tc: #%d, a: %d, b: %d", i, tc.a, tc.b,
+		)
+	}
+}
diff --git a/types/result.go b/types/result.go
index 20893a076fe3..924b73b49fbb 100644
--- a/types/result.go
+++ b/types/result.go
@@ -16,10 +16,10 @@ type Result struct {
 	Log string
 
 	// GasWanted is the maximum units of work we allow this tx to perform.
-	GasWanted int64
+	GasWanted uint64
 
 	// GasUsed is the amount of gas actually consumed. NOTE: unimplemented
-	GasUsed int64
+	GasUsed uint64
 
 	// Tx fee amount and denom.
 	FeeAmount int64
diff --git a/x/auth/ante.go b/x/auth/ante.go
index 8539be06a42f..7beb643c562c 100644
--- a/x/auth/ante.go
+++ b/x/auth/ante.go
@@ -71,6 +71,7 @@ func NewAnteHandler(am AccountKeeper, fck FeeCollectionKeeper) sdk.AnteHandler {
 		if err != nil {
 			return newCtx, err.Result(), true
 		}
+
 		// charge gas for the memo
 		newCtx.GasMeter().ConsumeGas(memoCostPerByte*sdk.Gas(len(stdTx.GetMemo())), "memo")
 
@@ -260,13 +261,16 @@ func consumeSignatureVerificationGas(meter sdk.GasMeter, pubkey crypto.PubKey) {
 	}
 }
 
-func adjustFeesByGas(fees sdk.Coins, gas int64) sdk.Coins {
+func adjustFeesByGas(fees sdk.Coins, gas uint64) sdk.Coins {
 	gasCost := gas / gasPerUnitCost
 	gasFees := make(sdk.Coins, len(fees))
+
 	// TODO: Make this not price all coins in the same way
+	// TODO: Undo int64 casting once unsigned integers are supported for coins
 	for i := 0; i < len(fees); i++ {
-		gasFees[i] = sdk.NewInt64Coin(fees[i].Denom, gasCost)
+		gasFees[i] = sdk.NewInt64Coin(fees[i].Denom, int64(gasCost))
 	}
+
 	return fees.Plus(gasFees)
 }
 
@@ -306,10 +310,12 @@ func ensureSufficientMempoolFees(ctx sdk.Context, stdTx StdTx) sdk.Result {
 }
 
 func setGasMeter(simulate bool, ctx sdk.Context, stdTx StdTx) sdk.Context {
-	// set the gas meter
+	// In various cases such as simulation and during the genesis block, we do not
+	// meter any gas utilization.
 	if simulate || ctx.BlockHeight() == 0 {
 		return ctx.WithGasMeter(sdk.NewInfiniteGasMeter())
 	}
+
 	return ctx.WithGasMeter(sdk.NewGasMeter(stdTx.Fee.Gas))
 }
 
diff --git a/x/auth/ante_test.go b/x/auth/ante_test.go
index c376d29961d4..0e8d13957a4f 100644
--- a/x/auth/ante_test.go
+++ b/x/auth/ante_test.go
@@ -677,7 +677,7 @@ func TestConsumeSignatureVerificationGas(t *testing.T) {
 	tests := []struct {
 		name        string
 		args        args
-		gasConsumed int64
+		gasConsumed uint64
 		wantPanic   bool
 	}{
 		{"PubKeyEd25519", args{sdk.NewInfiniteGasMeter(), ed25519.GenPrivKey().PubKey()}, ed25519VerifyCost, false},
@@ -699,7 +699,7 @@ func TestConsumeSignatureVerificationGas(t *testing.T) {
 func TestAdjustFeesByGas(t *testing.T) {
 	type args struct {
 		fee sdk.Coins
-		gas int64
+		gas uint64
 	}
 	tests := []struct {
 		name string
diff --git a/x/auth/client/txbuilder/txbuilder.go b/x/auth/client/txbuilder/txbuilder.go
index f516de4513d5..593d745abfeb 100644
--- a/x/auth/client/txbuilder/txbuilder.go
+++ b/x/auth/client/txbuilder/txbuilder.go
@@ -16,7 +16,7 @@ type TxBuilder struct {
 	Codec         *codec.Codec
 	AccountNumber int64
 	Sequence      int64
-	Gas           int64 // TODO: should this turn into uint64? requires further discussion - see #2173
+	Gas           uint64
 	GasAdjustment float64
 	SimulateGas   bool
 	ChainID       string
@@ -61,7 +61,7 @@ func (bldr TxBuilder) WithChainID(chainID string) TxBuilder {
 }
 
 // WithGas returns a copy of the context with an updated gas.
-func (bldr TxBuilder) WithGas(gas int64) TxBuilder {
+func (bldr TxBuilder) WithGas(gas uint64) TxBuilder {
 	bldr.Gas = gas
 	return bldr
 }
diff --git a/x/auth/client/txbuilder/txbuilder_test.go b/x/auth/client/txbuilder/txbuilder_test.go
index 3ad2ad4123d8..f4f9163a0303 100644
--- a/x/auth/client/txbuilder/txbuilder_test.go
+++ b/x/auth/client/txbuilder/txbuilder_test.go
@@ -9,8 +9,8 @@ import (
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/auth"
-	"github.com/tendermint/tendermint/crypto/ed25519"
 	stakeTypes "github.com/cosmos/cosmos-sdk/x/stake/types"
+	"github.com/tendermint/tendermint/crypto/ed25519"
 )
 
 var (
@@ -23,7 +23,7 @@ func TestTxBuilderBuild(t *testing.T) {
 		Codec         *codec.Codec
 		AccountNumber int64
 		Sequence      int64
-		Gas           int64
+		Gas           uint64
 		GasAdjustment float64
 		SimulateGas   bool
 		ChainID       string
diff --git a/x/auth/stdtx.go b/x/auth/stdtx.go
index 84bf88a4b7e5..ba1c65b84593 100644
--- a/x/auth/stdtx.go
+++ b/x/auth/stdtx.go
@@ -70,10 +70,10 @@ func (tx StdTx) GetSignatures() []StdSignature { return tx.Signatures }
 // which must be above some miminum to be accepted into the mempool.
 type StdFee struct {
 	Amount sdk.Coins `json:"amount"`
-	Gas    int64     `json:"gas"`
+	Gas    uint64    `json:"gas"`
 }
 
-func NewStdFee(gas int64, amount ...sdk.Coin) StdFee {
+func NewStdFee(gas uint64, amount ...sdk.Coin) StdFee {
 	return StdFee{
 		Amount: amount,
 		Gas:    gas,