diff --git a/CHANGELOG.md b/CHANGELOG.md
index bd1370ecd4e826024fa14a743c76a4ccc23439c9..9223991e6580ad50e904a58d104f9a9de424049c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 * Fixed media being permanently lost when transferring to an (effectively) readonly S3 datastore.
 * Purging non-existent files now won't cause errors.
+* Fixed HEIF/HEIC thumbnailing. Note that this thumbnail type might cause increased memory usage.
 
 ### Removed
 
diff --git a/go.mod b/go.mod
index a041e1654788c0bac4888bcdee75fbfe1c2ee050..fc0d45e4e77bd728158ea4bdbf85071db0dccf52 100644
--- a/go.mod
+++ b/go.mod
@@ -44,6 +44,7 @@ require (
 	github.com/ipfs/go-ipfs-config v0.12.0
 	github.com/ipfs/go-ipfs-files v0.0.8
 	github.com/ipfs/interface-go-ipfs-core v0.4.0
+	github.com/jdeng/goheif v0.0.0-20200323230657-a0d6a8b3e68f
 	github.com/jehiah/go-strftime v0.0.0-20171201141054-1d33003b3869 // indirect
 	github.com/k3a/html2text v1.0.7
 	github.com/kettek/apng v0.0.0-20191108220231-414630eed80f
diff --git a/go.sum b/go.sum
index 6c86f67efa1c9d496eb4678105f5af810f6a6ac6..1f9d94bb900e3bb520813388657ec47397715c39 100644
--- a/go.sum
+++ b/go.sum
@@ -675,6 +675,8 @@ github.com/jbenet/goprocess v0.1.3 h1:YKyIEECS/XvcfHtBzxtjBBbWK+MbvA6dG8ASiqwvr1
 github.com/jbenet/goprocess v0.1.3/go.mod h1:5yspPrukOVuOLORacaBi858NqyClJPQxYZlqdZVfqY4=
 github.com/jbenet/goprocess v0.1.4 h1:DRGOFReOMqqDNXwW70QkacFW0YN9QnwLV0Vqk+3oU0o=
 github.com/jbenet/goprocess v0.1.4/go.mod h1:5yspPrukOVuOLORacaBi858NqyClJPQxYZlqdZVfqY4=
+github.com/jdeng/goheif v0.0.0-20200323230657-a0d6a8b3e68f h1:jYkcRYsnnvPF07yn4XJx3k8duM4KDw3QYB3p8bUrk80=
+github.com/jdeng/goheif v0.0.0-20200323230657-a0d6a8b3e68f/go.mod h1:G7IyA3/eR9IFmUIPdyP3c0l4ZaqEvXAk876WfaQ8plc=
 github.com/jehiah/go-strftime v0.0.0-20171201141054-1d33003b3869 h1:IPJ3dvxmJ4uczJe5YQdrYB16oTJlGSC/OyZDqUk9xX4=
 github.com/jehiah/go-strftime v0.0.0-20171201141054-1d33003b3869/go.mod h1:cJ6Cj7dQo+O6GJNiMx+Pa94qKj+TG8ONdKHgMNIyyag=
 github.com/jellevandenhooff/dkim v0.0.0-20150330215556-f50fe3d243e1/go.mod h1:E0B/fFc00Y+Rasa88328GlI/XbtyysCtTHZS8h7IrBU=
diff --git a/thumbnailing/i/heif.go b/thumbnailing/i/heif.go
index 9a088aa1f215260bcb2055e6bcd2e940289a7e54..66da380021326379430acbe69d85a04693838326 100644
--- a/thumbnailing/i/heif.go
+++ b/thumbnailing/i/heif.go
@@ -1,6 +1,9 @@
 package i
 
 import (
+	"bytes"
+	"errors"
+	"github.com/jdeng/goheif"
 	"github.com/turt2live/matrix-media-repo/common/rcontext"
 	"github.com/turt2live/matrix-media-repo/thumbnailing/m"
 )
@@ -21,11 +24,23 @@ func (d heifGenerator) matches(img []byte, contentType string) bool {
 }
 
 func (d heifGenerator) GetOriginDimensions(b []byte, contentType string, ctx rcontext.RequestContext) (bool, int, int, error) {
-	return pngGenerator{}.GetOriginDimensions(b, contentType, ctx)
+	i, err := goheif.DecodeConfig(bytes.NewBuffer(b))
+	if err != nil {
+		return false, 0, 0, err
+	}
+	return true, i.Width, i.Height, nil
 }
 
 func (d heifGenerator) GenerateThumbnail(b []byte, contentType string, width int, height int, method string, animated bool, ctx rcontext.RequestContext) (*m.Thumbnail, error) {
-	return pngGenerator{}.GenerateThumbnail(b, "image/png", width, height, method, false, ctx)
+	// Use more memory, but prevent crashes
+	goheif.SafeEncoding = true
+
+	src, err := goheif.Decode(bytes.NewBuffer(b))
+	if err != nil {
+		return nil, errors.New("heif: error decoding thumbnail: " + err.Error())
+	}
+
+	return pngGenerator{}.GenerateThumbnailOf(src, width, height, method, ctx)
 }
 
 func init() {
diff --git a/thumbnailing/thumbnail.go b/thumbnailing/thumbnail.go
index 0f54122f870d391cdd02dd8b699cc54cec3e7acd..42bcaa037063931b1a125bac15b8c1d55a37c9fc 100644
--- a/thumbnailing/thumbnail.go
+++ b/thumbnailing/thumbnail.go
@@ -47,7 +47,8 @@ func GenerateThumbnail(imgStream io.ReadCloser, contentType string, width int, h
 	if err != nil {
 		return nil, err
 	}
-	if dimensional && (w * h) >= ctx.Config.Thumbnails.MaxPixels {
+	if dimensional && (w*h) >= ctx.Config.Thumbnails.MaxPixels {
+		ctx.Log.Warn("Image too large: too many pixels")
 		return nil, common.ErrMediaTooLarge
 	}