diff --git a/README.md b/README.md
index 91c66f9..6bdc6e3 100644
--- a/README.md
+++ b/README.md
@@ -4,14 +4,13 @@ This is a collection of packages which I use across many of my personal
 projects. All packages intended to be used start with an `m`, packages not
 starting with `m` are for internal use within this set of packages.
 
-Other third-party packages which integrate into these:
+## Usage notes
 
-* [merry](github.com/ansel1/merry): used by `mlog` to embed KV logging
-  information into `error` instances, it should be assumed that all errors
-  returned from these packages are `merry.Error` instances. In cases where a
-  package has a specific error it might return and which might be checked for a
-  function to perform that equality check will be supplied as part of the
-  package.
+* In general, all checking of equality of errors, e.g. `err == io.EOF`, done on
+  errors returned from the packages in this project should be done using
+  `merr.Equal`, e.g. `merr.Equal(err, io.EOF)`. The `merr` package is used to
+  wrap errors and embed further metadata in them, like stack traces and so
+  forth.
 
 ## Styleguide
 
diff --git a/mcrypto/pair.go b/mcrypto/pair.go
index 651f0ed..26648b5 100644
--- a/mcrypto/pair.go
+++ b/mcrypto/pair.go
@@ -13,7 +13,7 @@ import (
 	"math/big"
 	"time"
 
-	"github.com/mediocregopher/mediocre-go-lib/mlog"
+	"github.com/mediocregopher/mediocre-go-lib/merr"
 )
 
 var (
@@ -58,7 +58,7 @@ func (pk PublicKey) verify(s Signature, r io.Reader) error {
 		return err
 	}
 	if err := rsa.VerifyPSS(&pk.PublicKey, crypto.SHA256, h.Sum(nil), s.sig, nil); err != nil {
-		return mlog.ErrWithKV(ErrInvalidSig, s)
+		return merr.WithValue(ErrInvalidSig, "sig", s, true)
 	}
 	return nil
 }
@@ -88,12 +88,12 @@ func (pk *PublicKey) UnmarshalText(b []byte) error {
 	str := string(b)
 	strEnc, ok := stripPrefix(str, pubKeyV0)
 	if !ok || len(strEnc) <= hex.EncodedLen(8) {
-		return mlog.ErrWithKV(errMalformedPublicKey, mlog.KV{"pubKeyStr": str})
+		return merr.WithValue(errMalformedPublicKey, "pubKeyStr", str, true)
 	}
 
 	b, err := hex.DecodeString(strEnc)
 	if err != nil {
-		return mlog.ErrWithKV(err, mlog.KV{"pubKeyStr": str})
+		return merr.WithValue(err, "pubKeyStr", str, true)
 	}
 
 	pk.E = int(binary.BigEndian.Uint64(b))
@@ -184,17 +184,17 @@ func (pk *PrivateKey) UnmarshalText(b []byte) error {
 	str := string(b)
 	strEnc, ok := stripPrefix(str, privKeyV0)
 	if !ok {
-		return mlog.ErrWithKV(errMalformedPrivateKey, mlog.KV{"privKeyStr": str})
+		return merr.Wrap(errMalformedPrivateKey)
 	}
 
 	b, err := hex.DecodeString(strEnc)
 	if err != nil {
-		return mlog.ErrWithKV(err, mlog.KV{"privKeyStr": str})
+		return merr.Wrap(errMalformedPrivateKey)
 	}
 
 	e, n := binary.Uvarint(b)
 	if n <= 0 {
-		return mlog.ErrWithKV(errMalformedPrivateKey, mlog.KV{"privKeyStr": str})
+		return merr.Wrap(errMalformedPrivateKey)
 	}
 	pk.PublicKey.E = int(e)
 	b = b[n:]
@@ -205,7 +205,7 @@ func (pk *PrivateKey) UnmarshalText(b []byte) error {
 		}
 		l, n := binary.Uvarint(b)
 		if n <= 0 {
-			err = errMalformedPrivateKey
+			err = merr.Wrap(errMalformedPrivateKey)
 		}
 		b = b[n:]
 		i := new(big.Int)
@@ -221,7 +221,7 @@ func (pk *PrivateKey) UnmarshalText(b []byte) error {
 	}
 
 	if err != nil {
-		return mlog.ErrWithKV(err, mlog.KV{"privKeyStr": str})
+		return err
 	}
 	return nil
 }
diff --git a/mcrypto/secret.go b/mcrypto/secret.go
index 1511a90..156e12f 100644
--- a/mcrypto/secret.go
+++ b/mcrypto/secret.go
@@ -7,7 +7,7 @@ import (
 	"io"
 	"time"
 
-	"github.com/mediocregopher/mediocre-go-lib/mlog"
+	"github.com/mediocregopher/mediocre-go-lib/merr"
 )
 
 // Secret contains a set of bytes which are inteded to remain secret within some
@@ -76,9 +76,9 @@ func (s Secret) sign(r io.Reader) (Signature, error) {
 func (s Secret) verify(sig Signature, r io.Reader) error {
 	sigB, err := s.signRaw(r, uint8(len(sig.sig)), sig.salt, sig.t)
 	if err != nil {
-		return mlog.ErrWithKV(err, sig)
+		return merr.WithValue(err, "sig", sig, true)
 	} else if !hmac.Equal(sigB, sig.sig) {
-		return mlog.ErrWithKV(ErrInvalidSig, sig)
+		return merr.WithValue(ErrInvalidSig, "sig", sig, true)
 	}
 	return nil
 }
diff --git a/mcrypto/secret_test.go b/mcrypto/secret_test.go
index 1880197..9734ea5 100644
--- a/mcrypto/secret_test.go
+++ b/mcrypto/secret_test.go
@@ -4,7 +4,7 @@ import (
 	. "testing"
 	"time"
 
-	"github.com/ansel1/merry"
+	"github.com/mediocregopher/mediocre-go-lib/merr"
 	"github.com/mediocregopher/mediocre-go-lib/mrand"
 	"github.com/stretchr/testify/assert"
 )
@@ -43,9 +43,9 @@ func TestSecretSignVerify(t *T) {
 			assert.NotEqual(t, prevSig.String(), thisSigStr)
 			assert.NotEqual(t, prevWeakSig.String(), thisWeakSigStr)
 			err := VerifyString(secret, prevSig, thisStr)
-			assert.True(t, merry.Is(err, ErrInvalidSig))
+			assert.True(t, merr.Equal(err, ErrInvalidSig))
 			err = VerifyString(secret, prevWeakSig, thisStr)
-			assert.True(t, merry.Is(err, ErrInvalidSig))
+			assert.True(t, merr.Equal(err, ErrInvalidSig))
 		}
 		prevStr = thisStr
 		prevSig = thisSig
diff --git a/mcrypto/sig.go b/mcrypto/sig.go
index 42259ed..553ab96 100644
--- a/mcrypto/sig.go
+++ b/mcrypto/sig.go
@@ -9,7 +9,7 @@ import (
 	"io"
 	"time"
 
-	"github.com/mediocregopher/mediocre-go-lib/mlog"
+	"github.com/mediocregopher/mediocre-go-lib/merr"
 )
 
 var (
@@ -66,12 +66,12 @@ func (s *Signature) UnmarshalText(b []byte) error {
 	str := string(b)
 	strEnc, ok := stripPrefix(str, sigV0)
 	if !ok || len(strEnc) < hex.EncodedLen(10) {
-		return mlog.ErrWithKV(errMalformedSig, mlog.KV{"sigStr": str})
+		return merr.WithValue(errMalformedSig, "sigStr", str, true)
 	}
 
 	b, err := hex.DecodeString(strEnc)
 	if err != nil {
-		return mlog.ErrWithKV(err, mlog.KV{"sigStr": str})
+		return merr.WithValue(err, "sigStr", str, true)
 	}
 
 	unixNano, b := int64(binary.BigEndian.Uint64(b[:8])), b[8:]
@@ -81,7 +81,7 @@ func (s *Signature) UnmarshalText(b []byte) error {
 		if err != nil {
 			return nil
 		} else if len(b) < 1+int(b[0]) {
-			err = mlog.ErrWithKV(errMalformedSig, mlog.KV{"sigStr": str})
+			err = merr.WithValue(errMalformedSig, "sigStr", str, true)
 			return nil
 		}
 		out := b[1 : 1+b[0]]
diff --git a/mcrypto/sig_test.go b/mcrypto/sig_test.go
index dc60ffe..7a49c5d 100644
--- a/mcrypto/sig_test.go
+++ b/mcrypto/sig_test.go
@@ -4,7 +4,7 @@ import (
 	. "testing"
 	"time"
 
-	"github.com/ansel1/merry"
+	"github.com/mediocregopher/mediocre-go-lib/merr"
 	"github.com/mediocregopher/mediocre-go-lib/mrand"
 	"github.com/stretchr/testify/assert"
 )
@@ -36,7 +36,7 @@ func TestSignerVerifier(t *T) {
 		if prevStr != "" {
 			assert.NotEqual(t, prevSig.String(), thisSigStr)
 			err := VerifyString(secret, prevSig, thisStr)
-			assert.True(t, merry.Is(err, ErrInvalidSig))
+			assert.True(t, merr.Equal(err, ErrInvalidSig))
 		}
 		prevStr = thisStr
 		prevSig = thisSig
diff --git a/mcrypto/uuid.go b/mcrypto/uuid.go
index 2773e66..f898899 100644
--- a/mcrypto/uuid.go
+++ b/mcrypto/uuid.go
@@ -9,7 +9,7 @@ import (
 	"errors"
 	"time"
 
-	"github.com/mediocregopher/mediocre-go-lib/mlog"
+	"github.com/mediocregopher/mediocre-go-lib/merr"
 )
 
 var errMalformedUUID = errors.New("malformed UUID string")
@@ -68,11 +68,11 @@ func (u *UUID) UnmarshalText(b []byte) error {
 	str := string(b)
 	strEnc, ok := stripPrefix(str, uuidV0)
 	if !ok || len(strEnc) != hex.EncodedLen(16) {
-		return mlog.ErrWithKV(errMalformedUUID, mlog.KV{"uuidStr": str})
+		return merr.WithValue(errMalformedUUID, "uuidStr", str, true)
 	}
 	b, err := hex.DecodeString(strEnc)
 	if err != nil {
-		return mlog.ErrWithKV(err, mlog.KV{"uuidStr": str})
+		return merr.WithValue(err, "uuidStr", str, true)
 	}
 	u.b = b
 	return nil
diff --git a/mlog/errctx.go b/mlog/errctx.go
index da65c52..db256b4 100644
--- a/mlog/errctx.go
+++ b/mlog/errctx.go
@@ -2,52 +2,10 @@ package mlog
 
 import (
 	"context"
-	"fmt"
-	"path/filepath"
-
-	"github.com/ansel1/merry"
 )
 
 type kvKey int
 
-// ErrWithKV embeds the merging of a set of KVs into an error, returning a new
-// error instance. If the error already has a KV embedded in it then the
-// returned error will have the merging of them all, with the given KVs taking
-// precedence.
-func ErrWithKV(err error, kvs ...KVer) merry.Error {
-	if err == nil {
-		return nil
-	}
-	merr := merry.WrapSkipping(err, 1)
-	var kv KV
-	if exKV := merry.Value(merr, kvKey(0)); exKV != nil {
-		kv = mergeInto(exKV.(KV), kvs...)
-	} else {
-		kv = Merge(kvs...).KV()
-	}
-	return merr.WithValue(kvKey(0), kv)
-}
-
-// ErrKV returns a KV which includes the KV embedded in the error by ErrWithKV,
-// if any. The KV will also include an "err" field containing the output of
-// err.Error(), and an "errSrc" field if the given error is a merry error which
-// contains an embedded stacktrace.
-func ErrKV(err error) KVer {
-	var kv KV
-	if kvi := merry.Value(err, kvKey(0)); kvi != nil {
-		kv = kvi.(KV)
-	} else {
-		kv = KV{}
-	}
-	kv["err"] = err.Error()
-	if fileFull, line := merry.Location(err); fileFull != "" {
-		file, dir := filepath.Base(fileFull), filepath.Dir(fileFull)
-		dir = filepath.Base(dir) // only want the first dirname, ie the pkg name
-		kv["errSrc"] = fmt.Sprintf("%s/%s:%d", dir, file, line)
-	}
-	return kv
-}
-
 // CtxWithKV embeds a KV into a Context, returning a new Context instance. If
 // the Context already has a KV embedded in it then the returned error will have
 // the merging of the two, with the given KVs taking precedence.
diff --git a/mlog/errctx_test.go b/mlog/errctx_test.go
index 832121b..670a7c6 100644
--- a/mlog/errctx_test.go
+++ b/mlog/errctx_test.go
@@ -2,60 +2,11 @@ package mlog
 
 import (
 	"context"
-	"strings"
 	. "testing"
 
-	"github.com/ansel1/merry"
 	"github.com/mediocregopher/mediocre-go-lib/mtest/massert"
 )
 
-func TestErrKV(t *T) {
-	assertErrKV := func(err error, exp KV) massert.Assertion {
-		got := KV(ErrKV(err).KV())
-		errSrc := got["errSrc"]
-		delete(got, "errSrc")
-		return massert.All(
-			massert.Not(massert.Nil(errSrc)),
-			massert.Equal(true, strings.HasPrefix(errSrc.(string), "mlog/errctx_test.go")),
-			massert.Equal(exp, got),
-		)
-	}
-
-	err := merry.New("foo")
-	massert.Fatal(t, assertErrKV(err, KV{"err": err.Error()}))
-
-	kv := KV{"a": "a"}
-	err2 := ErrWithKV(err, kv)
-	massert.Fatal(t, massert.All(
-		assertErrKV(err, KV{"err": err.Error()}),
-		assertErrKV(err2, KV{"err": err.Error(), "a": "a"}),
-	))
-
-	// changing the kv now shouldn't do anything
-	kv["a"] = "b"
-	massert.Fatal(t, massert.All(
-		assertErrKV(err, KV{"err": err.Error()}),
-		assertErrKV(err2, KV{"err": err.Error(), "a": "a"}),
-	))
-
-	// a new ErrWithKV shouldn't affect the previous one
-	err3 := ErrWithKV(err2, KV{"b": "b"})
-	massert.Fatal(t, massert.All(
-		assertErrKV(err, KV{"err": err.Error()}),
-		assertErrKV(err2, KV{"err": err2.Error(), "a": "a"}),
-		assertErrKV(err3, KV{"err": err3.Error(), "a": "a", "b": "b"}),
-	))
-
-	// make sure precedence works
-	err4 := ErrWithKV(err3, KV{"b": "bb"})
-	massert.Fatal(t, massert.All(
-		assertErrKV(err, KV{"err": err.Error()}),
-		assertErrKV(err2, KV{"err": err2.Error(), "a": "a"}),
-		assertErrKV(err3, KV{"err": err3.Error(), "a": "a", "b": "b"}),
-		assertErrKV(err4, KV{"err": err4.Error(), "a": "a", "b": "bb"}),
-	))
-}
-
 func TestCtxKV(t *T) {
 	ctx := context.Background()
 	massert.Fatal(t, massert.Equal(KV{}, CtxKV(ctx)))
diff --git a/mlog/mlog.go b/mlog/mlog.go
index 6cc5448..f756311 100644
--- a/mlog/mlog.go
+++ b/mlog/mlog.go
@@ -10,7 +10,7 @@
 // Examples:
 //
 //	Info("Something important has occurred")
-//	Error("Could not open file", llog.KV{"filename": filename}, llog.ErrKV(err))
+//	Error("Could not open file", llog.KV{"filename": filename}, merr.KV(err))
 //
 package mlog
 
@@ -22,6 +22,8 @@ import (
 	"sort"
 	"strconv"
 	"sync"
+
+	"github.com/mediocregopher/mediocre-go-lib/merr"
 )
 
 // Truncate is a helper function to truncate a string to a given size. It will
@@ -339,7 +341,7 @@ func (l *Logger) Log(msg Message) {
 	}
 
 	if err := l.h(msg); err != nil {
-		go l.Error("Logger.Handler returned error", ErrKV(err))
+		go l.Error("Logger.Handler returned error", merr.KV(err))
 		return
 	}