diff --git a/file_signer.go b/file_signer.go
index 472fd59..835844b 100644
--- a/file_signer.go
+++ b/file_signer.go
@@ -8,9 +8,11 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"sync"
 )
 
 type fileSigner struct {
+	mu sync.Mutex
 }
 
 func NewFileBasedSigner() Signer {
@@ -118,6 +120,9 @@ func (f *fileSigner) hashFiles(tmpDir string) (map[string]string, error) {
 	}
 
 	ret := make(map[string]string)
+	f.mu.Lock()
+	defer f.mu.Unlock()
+
 	for name, data := range files {
 		hash := sha1.Sum(data)
 		ret[filepath.Base(name)] = fmt.Sprintf("%x", hash)
diff --git a/go.mod b/go.mod
index 9c55944..894b8b2 100644
--- a/go.mod
+++ b/go.mod
@@ -3,9 +3,9 @@ module github.com/alvinbaena/passkit
 go 1.17
 
 require (
-	go.mozilla.org/pkcs7 v0.0.0-20210826202110-33d05740a352
+	go.mozilla.org/pkcs7 v0.9.0
 	gopkg.in/go-playground/colors.v1 v1.2.0
-	software.sslmate.com/src/go-pkcs12 v0.4.0
+	software.sslmate.com/src/go-pkcs12 v0.5.0
 )
 
 require golang.org/x/crypto v0.17.0 // indirect
diff --git a/go.sum b/go.sum
index 5bf4ff2..08f0ae8 100644
--- a/go.sum
+++ b/go.sum
@@ -1,6 +1,8 @@
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 go.mozilla.org/pkcs7 v0.0.0-20210826202110-33d05740a352 h1:CCriYyAfq1Br1aIYettdHZTy8mBTIPo7We18TuO/bak=
 go.mozilla.org/pkcs7 v0.0.0-20210826202110-33d05740a352/go.mod h1:SNgMg+EgDFwmvSmLRTNKC5fegJjB7v23qTQ0XLGUNHk=
+go.mozilla.org/pkcs7 v0.9.0 h1:yM4/HS9dYv7ri2biPtxt8ikvB37a980dg69/pKmS+eI=
+go.mozilla.org/pkcs7 v0.9.0/go.mod h1:SNgMg+EgDFwmvSmLRTNKC5fegJjB7v23qTQ0XLGUNHk=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.11.0/go.mod h1:xgJhtzW8F9jGdVFWZESrid1U1bjeNy4zgy5cRr/CIio=
@@ -47,3 +49,5 @@ gopkg.in/go-playground/colors.v1 v1.2.0 h1:SPweMUve+ywPrfwao+UvfD5Ah78aOLUkT5RlJ
 gopkg.in/go-playground/colors.v1 v1.2.0/go.mod h1:AvbqcMpNXVl5gBrM20jBm3VjjKBbH/kI5UnqjU7lxFI=
 software.sslmate.com/src/go-pkcs12 v0.4.0 h1:H2g08FrTvSFKUj+D309j1DPfk5APnIdAQAB8aEykJ5k=
 software.sslmate.com/src/go-pkcs12 v0.4.0/go.mod h1:Qiz0EyvDRJjjxGyUQa2cCNZn/wMyzrRJ/qcDXOQazLI=
+software.sslmate.com/src/go-pkcs12 v0.5.0 h1:EC6R394xgENTpZ4RltKydeDUjtlM5drOYIG9c6TVj2M=
+software.sslmate.com/src/go-pkcs12 v0.5.0/go.mod h1:Qiz0EyvDRJjjxGyUQa2cCNZn/wMyzrRJ/qcDXOQazLI=
diff --git a/mem_signer.go b/mem_signer.go
index 24a4752..7f4c76d 100644
--- a/mem_signer.go
+++ b/mem_signer.go
@@ -6,9 +6,11 @@ import (
 	"crypto/sha1"
 	"encoding/json"
 	"fmt"
+	"sync"
 )
 
 type memorySigner struct {
+	mu sync.Mutex
 }
 
 func NewMemoryBasedSigner() Signer {
@@ -24,6 +26,9 @@ func (m *memorySigner) CreateSignedAndZippedPersonalizedPassArchive(p *Pass, pz
 	if err != nil {
 		return nil, err
 	}
+
+	m.mu.Lock()
+	defer m.mu.Unlock()
 	files := m.makeFilesCopy(originalFiles)
 
 	if !p.IsValid() {
diff --git a/templates.go b/templates.go
index c3cf780..3022637 100644
--- a/templates.go
+++ b/templates.go
@@ -7,6 +7,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 )
 
@@ -67,6 +68,7 @@ func (f *FolderPassTemplate) GetAllFiles() (map[string][]byte, error) {
 
 type InMemoryPassTemplate struct {
 	files map[string][]byte
+	mu    sync.Mutex
 }
 
 func NewInMemoryPassTemplate() *InMemoryPassTemplate {
@@ -87,7 +89,7 @@ func (m *InMemoryPassTemplate) ProvisionPassAtDirectory(tmpDirPath string) error
 	}
 
 	for file, d := range m.files {
-		err = os.WriteFile(filepath.Join(dst, string(file)), d, 0644)
+		err = os.WriteFile(filepath.Join(dst, file), d, 0644)
 		if err != nil {
 			_ = os.RemoveAll(dst)
 			return err
@@ -102,10 +104,14 @@ func (m *InMemoryPassTemplate) GetAllFiles() (map[string][]byte, error) {
 }
 
 func (m *InMemoryPassTemplate) AddFileBytes(name string, data []byte) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
 	m.files[name] = data
 }
 
 func (m *InMemoryPassTemplate) AddFileBytesLocalized(name, locale string, data []byte) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
 	m.files[m.pathForLocale(name, locale)] = data
 }
 
@@ -137,6 +143,8 @@ func (m *InMemoryPassTemplate) AddFileFromURL(name string, u url.URL) error {
 		return err
 	}
 
+	m.mu.Lock()
+	defer m.mu.Unlock()
 	m.files[name] = b
 	return nil
 }
@@ -147,6 +155,8 @@ func (m *InMemoryPassTemplate) AddFileFromURLLocalized(name, locale string, u ur
 		return err
 	}
 
+	m.mu.Lock()
+	defer m.mu.Unlock()
 	m.files[m.pathForLocale(name, locale)] = b
 	return nil
 }
@@ -158,6 +168,8 @@ func (m *InMemoryPassTemplate) AddAllFiles(directoryWithFilesToAdd string) error
 		return err
 	}
 
+	m.mu.Lock()
+	defer m.mu.Unlock()
 	for name, data := range loaded {
 		m.files[filepath.Base(name)] = data
 	}