diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 7dfe9552..4c3d8bde 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -19,7 +19,7 @@ jobs:
       - name: "setup go"
         uses: "actions/setup-go@v3"
         with:
-          go-version: "1.20"
+          go-version: "1.21"
       - name: "install python3-pytest"
         run: "sudo apt install -y python3-pytest"
       - name: "make install"
diff --git a/Dockerfile b/Dockerfile
index 06cc93f1..5eaec3ec 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
 ## build ergo binary
-FROM golang:1.20-alpine AS build-env
+FROM golang:1.21-alpine AS build-env
 
 RUN apk upgrade -U --force-refresh --no-cache && apk add --no-cache --purge --clean-protected -l -u make git
 
diff --git a/go.mod b/go.mod
index 73fedb42..90422a6a 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/ergochat/ergo
 
-go 1.20
+go 1.21
 
 require (
 	code.cloudfoundry.org/bytefmt v0.0.0-20200131002437-cf55d5288a48
diff --git a/irc/channel.go b/irc/channel.go
index 4680958c..4dc5bccb 100644
--- a/irc/channel.go
+++ b/irc/channel.go
@@ -7,6 +7,7 @@ package irc
 
 import (
 	"fmt"
+	"maps"
 	"strconv"
 	"strings"
 	"time"
@@ -158,7 +159,7 @@ func (channel *Channel) ExportRegistration() (info RegisteredChannel) {
 	info.Bans = channel.lists[modes.BanMask].Masks()
 	info.Invites = channel.lists[modes.InviteMask].Masks()
 	info.Excepts = channel.lists[modes.ExceptMask].Masks()
-	info.AccountToUMode = utils.CopyMap(channel.accountToUMode)
+	info.AccountToUMode = maps.Clone(channel.accountToUMode)
 
 	info.Settings = channel.settings
 
diff --git a/irc/chanserv.go b/irc/chanserv.go
index 6e8389ab..a8360c03 100644
--- a/irc/chanserv.go
+++ b/irc/chanserv.go
@@ -6,6 +6,7 @@ package irc
 import (
 	"fmt"
 	"regexp"
+	"slices"
 	"sort"
 	"strings"
 	"time"
@@ -218,7 +219,7 @@ func csAmodeHandler(service *ircService, server *Server, client *Client, command
 	// check for anything valid as a channel mode change that is not valid
 	// as an AMODE change
 	for _, modeChange := range modeChanges {
-		if !utils.SliceContains(modes.ChannelUserModes, modeChange.Mode) {
+		if !slices.Contains(modes.ChannelUserModes, modeChange.Mode) {
 			invalid = true
 		}
 	}
diff --git a/irc/client.go b/irc/client.go
index 237b5aad..80a60a23 100644
--- a/irc/client.go
+++ b/irc/client.go
@@ -8,6 +8,7 @@ package irc
 import (
 	"crypto/x509"
 	"fmt"
+	"maps"
 	"net"
 	"runtime/debug"
 	"strconv"
@@ -1743,7 +1744,7 @@ func (client *Client) handleRegisterTimeout() {
 func (client *Client) copyLastSeen() (result map[string]time.Time) {
 	client.stateMutex.RLock()
 	defer client.stateMutex.RUnlock()
-	return utils.CopyMap(client.lastSeen)
+	return maps.Clone(client.lastSeen)
 }
 
 // these are bit flags indicating what part of the client status is "dirty"
diff --git a/irc/fakelag.go b/irc/fakelag.go
index 25ef0609..4a533981 100644
--- a/irc/fakelag.go
+++ b/irc/fakelag.go
@@ -4,9 +4,8 @@
 package irc
 
 import (
+	"maps"
 	"time"
-
-	"github.com/ergochat/ergo/irc/utils"
 )
 
 // fakelag is a system for artificially delaying commands when a user issues
@@ -40,7 +39,7 @@ func (fl *Fakelag) Initialize(config FakelagConfig) {
 	fl.config = config
 	// XXX don't share mutable member CommandBudgets:
 	if config.CommandBudgets != nil {
-		fl.config.CommandBudgets = utils.CopyMap(config.CommandBudgets)
+		fl.config.CommandBudgets = maps.Clone(config.CommandBudgets)
 	}
 	fl.nowFunc = time.Now
 	fl.sleepFunc = time.Sleep
diff --git a/irc/getters.go b/irc/getters.go
index 19b162f4..baf86cc6 100644
--- a/irc/getters.go
+++ b/irc/getters.go
@@ -5,6 +5,7 @@ package irc
 
 import (
 	"fmt"
+	"maps"
 	"net"
 	"time"
 
@@ -515,7 +516,7 @@ func (client *Client) GetReadMarker(cfname string) (result string) {
 func (client *Client) copyReadMarkers() (result map[string]time.Time) {
 	client.stateMutex.RLock()
 	defer client.stateMutex.RUnlock()
-	return utils.CopyMap(client.readMarkers)
+	return maps.Clone(client.readMarkers)
 }
 
 func (client *Client) SetReadMarker(cfname string, now time.Time) (result time.Time) {
diff --git a/irc/history/history.go b/irc/history/history.go
index 75d6298d..ef7e4d9f 100644
--- a/irc/history/history.go
+++ b/irc/history/history.go
@@ -4,6 +4,7 @@
 package history
 
 import (
+	"slices"
 	"sync"
 	"time"
 
@@ -155,7 +156,7 @@ func (list *Buffer) betweenHelper(start, end Selector, cutoff time.Time, pred Pr
 
 	defer func() {
 		if !ascending {
-			utils.ReverseSlice(results)
+			slices.Reverse(results)
 		}
 	}()
 
@@ -262,7 +263,7 @@ func (list *Buffer) listCorrespondents(start, end Selector, cutoff time.Time, li
 	}
 
 	if !ascending {
-		utils.ReverseSlice(results)
+		slices.Reverse(results)
 	}
 
 	return
diff --git a/irc/history/targets.go b/irc/history/targets.go
index 39a8c635..d2fdf67c 100644
--- a/irc/history/targets.go
+++ b/irc/history/targets.go
@@ -4,10 +4,9 @@
 package history
 
 import (
+	"slices"
 	"sort"
 	"time"
-
-	"github.com/ergochat/ergo/irc/utils"
 )
 
 type TargetListing struct {
@@ -35,8 +34,8 @@ func MergeTargets(base []TargetListing, extra []TargetListing, start, end time.T
 	results = make([]TargetListing, 0, prealloc)
 
 	if !ascending {
-		utils.ReverseSlice(base)
-		utils.ReverseSlice(extra)
+		slices.Reverse(base)
+		slices.Reverse(extra)
 	}
 
 	for len(results) < limit {
@@ -66,7 +65,7 @@ func MergeTargets(base []TargetListing, extra []TargetListing, start, end time.T
 	}
 
 	if !ascending {
-		utils.ReverseSlice(results)
+		slices.Reverse(results)
 	}
 	return
 }
diff --git a/irc/mysql/history.go b/irc/mysql/history.go
index 4cb985f4..4b967104 100644
--- a/irc/mysql/history.go
+++ b/irc/mysql/history.go
@@ -11,6 +11,7 @@ import (
 	"fmt"
 	"io"
 	"runtime/debug"
+	"slices"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -917,7 +918,7 @@ func (mysql *MySQL) betweenTimestamps(ctx context.Context, target, correspondent
 
 	results, err = mysql.selectItems(ctx, queryBuf.String(), args...)
 	if err == nil && !ascending {
-		utils.ReverseSlice(results)
+		slices.Reverse(results)
 	}
 	return
 }
@@ -965,7 +966,7 @@ func (mysql *MySQL) listCorrespondentsInternal(ctx context.Context, target strin
 	}
 
 	if !ascending {
-		utils.ReverseSlice(results)
+		slices.Reverse(results)
 	}
 
 	return
diff --git a/irc/utils/types.go b/irc/utils/types.go
index 8c2ca4eb..8d136f34 100644
--- a/irc/utils/types.go
+++ b/irc/utils/types.go
@@ -27,27 +27,3 @@ func SetLiteral[T comparable](elems ...T) HashSet[T] {
 	}
 	return result
 }
-
-func CopyMap[K comparable, V any](input map[K]V) (result map[K]V) {
-	result = make(map[K]V, len(input))
-	for key, value := range input {
-		result[key] = value
-	}
-	return
-}
-
-// reverse the order of a slice in place
-func ReverseSlice[T any](results []T) {
-	for i, j := 0, len(results)-1; i < j; i, j = i+1, j-1 {
-		results[i], results[j] = results[j], results[i]
-	}
-}
-
-func SliceContains[T comparable](slice []T, elem T) (result bool) {
-	for _, t := range slice {
-		if elem == t {
-			return true
-		}
-	}
-	return false
-}