diff --git a/client/grpc_client.go b/client/grpc_client.go
index c48ebbcb5..3f568ac28 100644
--- a/client/grpc_client.go
+++ b/client/grpc_client.go
@@ -1,6 +1,7 @@
 package abcicli
 
 import (
+	"fmt"
 	"net"
 	"sync"
 	"time"
@@ -50,7 +51,7 @@ RETRY_LOOP:
 			if cli.mustConnect {
 				return err
 			} else {
-				log.Warn(common.Fmt("abci.grpcClient failed to connect to %v.  Retrying...\n", cli.addr))
+				log.Warn(fmt.Sprintf("abci.grpcClient failed to connect to %v.  Retrying...\n", cli.addr))
 				time.Sleep(time.Second * 3)
 				continue RETRY_LOOP
 			}
@@ -93,7 +94,7 @@ func (cli *grpcClient) StopForError(err error) {
 	}
 	cli.mtx.Unlock()
 
-	log.Warn(common.Fmt("Stopping abci.grpcClient for error: %v", err.Error()))
+	log.Warn(fmt.Sprintf("Stopping abci.grpcClient for error: %v", err.Error()))
 	cli.Stop()
 }
 
diff --git a/client/socket_client.go b/client/socket_client.go
index 9309b67ad..2ed51ef42 100644
--- a/client/socket_client.go
+++ b/client/socket_client.go
@@ -70,7 +70,7 @@ RETRY_LOOP:
 			if cli.mustConnect {
 				return err
 			} else {
-				log.Warn(common.Fmt("abci.socketClient failed to connect to %v.  Retrying...", cli.addr))
+				log.Warn(fmt.Sprintf("abci.socketClient failed to connect to %v.  Retrying...", cli.addr))
 				time.Sleep(time.Second * 3)
 				continue RETRY_LOOP
 			}
@@ -109,7 +109,7 @@ func (cli *socketClient) StopForError(err error) {
 	}
 	cli.mtx.Unlock()
 
-	log.Warn(common.Fmt("Stopping abci.socketClient for error: %v", err.Error()))
+	log.Warn(fmt.Sprintf("Stopping abci.socketClient for error: %v", err.Error()))
 	cli.Stop()
 }
 
diff --git a/cmd/abci-cli/tmsp-cli.go b/cmd/abci-cli/tmsp-cli.go
index 99d22a086..d2227a68d 100644
--- a/cmd/abci-cli/tmsp-cli.go
+++ b/cmd/abci-cli/tmsp-cli.go
@@ -244,7 +244,7 @@ func cmdSetOption(c *cli.Context) error {
 		return errors.New("Command set_option takes 2 arguments (key, value)")
 	}
 	res := client.SetOptionSync(args[0], args[1])
-	rsp := newResponse(res, common.Fmt("%s=%s", args[0], args[1]), false)
+	rsp := newResponse(res, fmt.Sprintf("%s=%s", args[0], args[1]), false)
 	printResponse(c, rsp)
 	return nil
 }
@@ -284,7 +284,7 @@ func cmdCheckTx(c *cli.Context) error {
 // Get application Merkle root hash
 func cmdCommit(c *cli.Context) error {
 	res := client.CommitSync()
-	rsp := newResponse(res, common.Fmt("0x%X", res.Data), false)
+	rsp := newResponse(res, fmt.Sprintf("0x%X", res.Data), false)
 	printResponse(c, rsp)
 	return nil
 }
diff --git a/example/chain_aware/chain_aware_app.go b/example/chain_aware/chain_aware_app.go
index c0dc0d6e0..534135d1b 100644
--- a/example/chain_aware/chain_aware_app.go
+++ b/example/chain_aware/chain_aware_app.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"flag"
+	"fmt"
 
 	"github.com/tendermint/abci/server"
 	"github.com/tendermint/abci/types"
@@ -58,7 +59,7 @@ func (app *ChainAwareApplication) Commit() types.Result {
 }
 
 func (app *ChainAwareApplication) Query(query []byte) types.Result {
-	return types.NewResultOK([]byte(common.Fmt("%d,%d", app.beginCount, app.endCount)), "")
+	return types.NewResultOK([]byte(fmt.Sprintf("%d,%d", app.beginCount, app.endCount)), "")
 }
 
 func (app *ChainAwareApplication) BeginBlock(hash []byte, header *types.Header) {
diff --git a/example/counter/counter.go b/example/counter/counter.go
index 02ff00ee9..03861d0f7 100644
--- a/example/counter/counter.go
+++ b/example/counter/counter.go
@@ -2,9 +2,9 @@ package counter
 
 import (
 	"encoding/binary"
+	"fmt"
 
 	"github.com/tendermint/abci/types"
-	common "github.com/tendermint/go-common"
 )
 
 type CounterApplication struct {
@@ -18,7 +18,7 @@ func NewCounterApplication(serial bool) *CounterApplication {
 }
 
 func (app *CounterApplication) Info() types.ResponseInfo {
-	return types.ResponseInfo{Data: common.Fmt("{\"hashes\":%v,\"txs\":%v}", app.hashCount, app.txCount)}
+	return types.ResponseInfo{Data: fmt.Sprintf("{\"hashes\":%v,\"txs\":%v}", app.hashCount, app.txCount)}
 }
 
 func (app *CounterApplication) SetOption(key string, value string) (log string) {
@@ -31,13 +31,13 @@ func (app *CounterApplication) SetOption(key string, value string) (log string)
 func (app *CounterApplication) DeliverTx(tx []byte) types.Result {
 	if app.serial {
 		if len(tx) > 8 {
-			return types.ErrEncodingError.SetLog(common.Fmt("Max tx size is 8 bytes, got %d", len(tx)))
+			return types.ErrEncodingError.SetLog(fmt.Sprintf("Max tx size is 8 bytes, got %d", len(tx)))
 		}
 		tx8 := make([]byte, 8)
 		copy(tx8[len(tx8)-len(tx):], tx)
 		txValue := binary.BigEndian.Uint64(tx8)
 		if txValue != uint64(app.txCount) {
-			return types.ErrBadNonce.SetLog(common.Fmt("Invalid nonce. Expected %v, got %v", app.txCount, txValue))
+			return types.ErrBadNonce.SetLog(fmt.Sprintf("Invalid nonce. Expected %v, got %v", app.txCount, txValue))
 		}
 	}
 	app.txCount += 1
@@ -47,13 +47,13 @@ func (app *CounterApplication) DeliverTx(tx []byte) types.Result {
 func (app *CounterApplication) CheckTx(tx []byte) types.Result {
 	if app.serial {
 		if len(tx) > 8 {
-			return types.ErrEncodingError.SetLog(common.Fmt("Max tx size is 8 bytes, got %d", len(tx)))
+			return types.ErrEncodingError.SetLog(fmt.Sprintf("Max tx size is 8 bytes, got %d", len(tx)))
 		}
 		tx8 := make([]byte, 8)
 		copy(tx8[len(tx8)-len(tx):], tx)
 		txValue := binary.BigEndian.Uint64(tx8)
 		if txValue < uint64(app.txCount) {
-			return types.ErrBadNonce.SetLog(common.Fmt("Invalid nonce. Expected >= %v, got %v", app.txCount, txValue))
+			return types.ErrBadNonce.SetLog(fmt.Sprintf("Invalid nonce. Expected >= %v, got %v", app.txCount, txValue))
 		}
 	}
 	return types.OK
@@ -76,10 +76,10 @@ func (app *CounterApplication) Query(query []byte) types.Result {
 
 	switch queryStr {
 	case "hash":
-		return types.NewResultOK(nil, common.Fmt("%v", app.hashCount))
+		return types.NewResultOK(nil, fmt.Sprintf("%v", app.hashCount))
 	case "tx":
-		return types.NewResultOK(nil, common.Fmt("%v", app.txCount))
+		return types.NewResultOK(nil, fmt.Sprintf("%v", app.txCount))
 	}
 
-	return types.ErrUnknownRequest.SetLog(common.Fmt("Invalid nonce. Expected hash or tx, got %v", queryStr))
+	return types.ErrUnknownRequest.SetLog(fmt.Sprintf("Invalid nonce. Expected hash or tx, got %v", queryStr))
 }
diff --git a/example/dummy/dummy.go b/example/dummy/dummy.go
index c49353e1b..b514e43c3 100644
--- a/example/dummy/dummy.go
+++ b/example/dummy/dummy.go
@@ -2,10 +2,10 @@ package dummy
 
 import (
 	"encoding/hex"
+	"fmt"
 	"strings"
 
 	"github.com/tendermint/abci/types"
-	common "github.com/tendermint/go-common"
 	"github.com/tendermint/go-merkle"
 	"github.com/tendermint/go-wire"
 )
@@ -20,7 +20,7 @@ func NewDummyApplication() *DummyApplication {
 }
 
 func (app *DummyApplication) Info() (resInfo types.ResponseInfo) {
-	return types.ResponseInfo{Data: common.Fmt("{\"size\":%v}", app.state.Size())}
+	return types.ResponseInfo{Data: fmt.Sprintf("{\"size\":%v}", app.state.Size())}
 }
 
 func (app *DummyApplication) SetOption(key string, value string) (log string) {
diff --git a/example/dummy/dummy_test.go b/example/dummy/dummy_test.go
index 9236068e8..ca1ec7f92 100644
--- a/example/dummy/dummy_test.go
+++ b/example/dummy/dummy_test.go
@@ -2,6 +2,7 @@ package dummy
 
 import (
 	"bytes"
+	"fmt"
 	"io/ioutil"
 	"sort"
 	"testing"
@@ -107,7 +108,7 @@ func TestValSetChanges(t *testing.T) {
 	nInit := 5
 	vals := make([]*types.Validator, total)
 	for i := 0; i < total; i++ {
-		pubkey := crypto.GenPrivKeyEd25519FromSecret([]byte(common.Fmt("test%d", i))).PubKey().Bytes()
+		pubkey := crypto.GenPrivKeyEd25519FromSecret([]byte(fmt.Sprintf("test%d", i))).PubKey().Bytes()
 		power := common.RandInt()
 		vals[i] = &types.Validator{pubkey, uint64(power)}
 	}
diff --git a/example/dummy/persistent_dummy.go b/example/dummy/persistent_dummy.go
index b7c1eb4bb..f7302b9de 100644
--- a/example/dummy/persistent_dummy.go
+++ b/example/dummy/persistent_dummy.go
@@ -3,6 +3,7 @@ package dummy
 import (
 	"bytes"
 	"encoding/hex"
+	"fmt"
 	"strconv"
 	"strings"
 
@@ -135,7 +136,7 @@ func LoadLastBlock(db dbm.DB) (lastBlock LastBlockInfo) {
 		wire.ReadBinaryPtr(&lastBlock, r, 0, n, err)
 		if *err != nil {
 			// DATA HAS BEEN CORRUPTED OR THE SPEC HAS CHANGED
-			common.Exit(common.Fmt("Data has been corrupted or its spec has changed: %v\n", *err))
+			common.Exit(fmt.Sprintf("Data has been corrupted or its spec has changed: %v\n", *err))
 		}
 		// TODO: ensure that buf is completely read.
 	}
@@ -173,7 +174,7 @@ func (app *PersistentDummyApplication) Validators() (validators []*types.Validat
 }
 
 func MakeValSetChangeTx(pubkey []byte, power uint64) []byte {
-	return []byte(common.Fmt("val:%X/%d", pubkey, power))
+	return []byte(fmt.Sprintf("val:%X/%d", pubkey, power))
 }
 
 func isValidatorTx(tx []byte) bool {
@@ -188,16 +189,16 @@ func (app *PersistentDummyApplication) execValidatorTx(tx []byte) types.Result {
 	tx = tx[len(ValidatorSetChangePrefix):]
 	pubKeyAndPower := strings.Split(string(tx), "/")
 	if len(pubKeyAndPower) != 2 {
-		return types.ErrEncodingError.SetLog(common.Fmt("Expected 'pubkey/power'. Got %v", pubKeyAndPower))
+		return types.ErrEncodingError.SetLog(fmt.Sprintf("Expected 'pubkey/power'. Got %v", pubKeyAndPower))
 	}
 	pubkeyS, powerS := pubKeyAndPower[0], pubKeyAndPower[1]
 	pubkey, err := hex.DecodeString(pubkeyS)
 	if err != nil {
-		return types.ErrEncodingError.SetLog(common.Fmt("Pubkey (%s) is invalid hex", pubkeyS))
+		return types.ErrEncodingError.SetLog(fmt.Sprintf("Pubkey (%s) is invalid hex", pubkeyS))
 	}
 	power, err := strconv.Atoi(powerS)
 	if err != nil {
-		return types.ErrEncodingError.SetLog(common.Fmt("Power (%s) is not an int", powerS))
+		return types.ErrEncodingError.SetLog(fmt.Sprintf("Power (%s) is not an int", powerS))
 	}
 
 	// update
@@ -210,14 +211,14 @@ func (app *PersistentDummyApplication) updateValidator(v *types.Validator) types
 	if v.Power == 0 {
 		// remove validator
 		if !app.app.state.Has(key) {
-			return types.ErrUnauthorized.SetLog(common.Fmt("Cannot remove non-existent validator %X", key))
+			return types.ErrUnauthorized.SetLog(fmt.Sprintf("Cannot remove non-existent validator %X", key))
 		}
 		app.app.state.Remove(key)
 	} else {
 		// add or update validator
 		value := bytes.NewBuffer(make([]byte, 0))
 		if err := types.WriteMessage(v, value); err != nil {
-			return types.ErrInternalError.SetLog(common.Fmt("Error encoding validator: %v", err))
+			return types.ErrInternalError.SetLog(fmt.Sprintf("Error encoding validator: %v", err))
 		}
 		app.app.state.Set(key, value.Bytes())
 	}
diff --git a/example/example_test.go b/example/example_test.go
index 945499943..f47962fb1 100644
--- a/example/example_test.go
+++ b/example/example_test.go
@@ -41,14 +41,14 @@ func testStream(t *testing.T, app types.Application) {
 	// Start the listener
 	server, err := server.NewSocketServer("unix://test.sock", app)
 	if err != nil {
-		common.Exit(common.Fmt("Error starting socket server: %v", err.Error()))
+		common.Exit(fmt.Sprintf("Error starting socket server: %v", err.Error()))
 	}
 	defer server.Stop()
 
 	// Connect to the socket
 	client, err := abcicli.NewSocketClient("unix://test.sock", false)
 	if err != nil {
-		common.Exit(common.Fmt("Error starting socket client: %v", err.Error()))
+		common.Exit(fmt.Sprintf("Error starting socket client: %v", err.Error()))
 	}
 	client.Start()
 	defer client.Stop()
@@ -114,14 +114,14 @@ func testGRPCSync(t *testing.T, app *types.GRPCApplication) {
 	// Start the listener
 	server, err := server.NewGRPCServer("unix://test.sock", app)
 	if err != nil {
-		common.Exit(common.Fmt("Error starting GRPC server: %v", err.Error()))
+		common.Exit(fmt.Sprintf("Error starting GRPC server: %v", err.Error()))
 	}
 	defer server.Stop()
 
 	// Connect to the socket
 	conn, err := grpc.Dial("unix://test.sock", grpc.WithInsecure(), grpc.WithDialer(dialerFunc))
 	if err != nil {
-		common.Exit(common.Fmt("Error dialing GRPC server: %v", err.Error()))
+		common.Exit(fmt.Sprintf("Error dialing GRPC server: %v", err.Error()))
 	}
 	defer conn.Close()
 
diff --git a/tests/benchmarks/simple/simple.go b/tests/benchmarks/simple/simple.go
index 5076dc7a1..d99c1b561 100644
--- a/tests/benchmarks/simple/simple.go
+++ b/tests/benchmarks/simple/simple.go
@@ -62,7 +62,7 @@ func makeRequest(conn net.Conn, req *types.Request) (*types.Response, error) {
 		return nil, err
 	}
 	if _, ok := resFlush.Value.(*types.Response_Flush); !ok {
-		return nil, errors.New(common.Fmt("Expected flush response but got something else: %v", reflect.TypeOf(resFlush)))
+		return nil, errors.New(fmt.Sprintf("Expected flush response but got something else: %v", reflect.TypeOf(resFlush)))
 	}
 
 	return res, nil
diff --git a/tests/test_app/app.go b/tests/test_app/app.go
index ef9322788..8651cd4ba 100644
--- a/tests/test_app/app.go
+++ b/tests/test_app/app.go
@@ -46,7 +46,7 @@ func SetOption(client abcicli.Client, key, value string) {
 	res := client.SetOptionSync(key, value)
 	_, _, log := res.Code, res.Data, res.Log
 	if res.IsErr() {
-		panic(common.Fmt("setting %v=%v: \nlog: %v", key, value, log))
+		panic(fmt.Sprintf("setting %v=%v: \nlog: %v", key, value, log))
 	}
 }
 
@@ -54,10 +54,10 @@ func Commit(client abcicli.Client, hashExp []byte) {
 	res := client.CommitSync()
 	_, data, log := res.Code, res.Data, res.Log
 	if res.IsErr() {
-		panic(common.Fmt("committing %v\nlog: %v", log))
+		panic(fmt.Sprintf("committing %v\nlog: %v", log))
 	}
 	if !bytes.Equal(res.Data, hashExp) {
-		panic(common.Fmt("Commit hash was unexpected. Got %X expected %X",
+		panic(fmt.Sprintf("Commit hash was unexpected. Got %X expected %X",
 			data, hashExp))
 	}
 }
@@ -66,11 +66,11 @@ func DeliverTx(client abcicli.Client, txBytes []byte, codeExp types.CodeType, da
 	res := client.DeliverTxSync(txBytes)
 	code, data, log := res.Code, res.Data, res.Log
 	if code != codeExp {
-		panic(common.Fmt("DeliverTx response code was unexpected. Got %v expected %v. Log: %v",
+		panic(fmt.Sprintf("DeliverTx response code was unexpected. Got %v expected %v. Log: %v",
 			code, codeExp, log))
 	}
 	if !bytes.Equal(data, dataExp) {
-		panic(common.Fmt("DeliverTx response data was unexpected. Got %X expected %X",
+		panic(fmt.Sprintf("DeliverTx response data was unexpected. Got %X expected %X",
 			data, dataExp))
 	}
 }
@@ -79,14 +79,14 @@ func CheckTx(client abcicli.Client, txBytes []byte, codeExp types.CodeType, data
 	res := client.CheckTxSync(txBytes)
 	code, data, log := res.Code, res.Data, res.Log
 	if res.IsErr() {
-		panic(common.Fmt("checking tx %X: %v\nlog: %v", txBytes, log))
+		panic(fmt.Sprintf("checking tx %X: %v\nlog: %v", txBytes, log))
 	}
 	if code != codeExp {
-		panic(common.Fmt("CheckTx response code was unexpected. Got %v expected %v. Log: %v",
+		panic(fmt.Sprintf("CheckTx response code was unexpected. Got %v expected %v. Log: %v",
 			code, codeExp, log))
 	}
 	if !bytes.Equal(data, dataExp) {
-		panic(common.Fmt("CheckTx response data was unexpected. Got %X expected %X",
+		panic(fmt.Sprintf("CheckTx response data was unexpected. Got %X expected %X",
 			data, dataExp))
 	}
 }