diff --git a/internal/chezmoi/path_unix.go b/internal/chezmoi/path_unix.go
index bcee9f6e03b..bc9db148674 100644
--- a/internal/chezmoi/path_unix.go
+++ b/internal/chezmoi/path_unix.go
@@ -12,6 +12,7 @@ var devNullAbsPath = NewAbsPath("/dev/null")
 // NewAbsPathFromExtPath returns a new AbsPath by converting extPath to use
 // slashes, performing tilde expansion, and making the path absolute.
 func NewAbsPathFromExtPath(extPath string, homeDirAbsPath AbsPath) (AbsPath, error) {
+	extPath = filepath.Clean(extPath)
 	switch {
 	case extPath == "~":
 		return homeDirAbsPath, nil
diff --git a/internal/chezmoi/path_windows.go b/internal/chezmoi/path_windows.go
index 3a9f2dbff3f..fb6b7eb582e 100644
--- a/internal/chezmoi/path_windows.go
+++ b/internal/chezmoi/path_windows.go
@@ -11,6 +11,7 @@ var devNullAbsPath = NewAbsPath("NUL:")
 // slashes, performing tilde expansion, making the path absolute, and converting
 // the volume name to uppercase.
 func NewAbsPathFromExtPath(extPath string, homeDirAbsPath AbsPath) (AbsPath, error) {
+	extPath = filepath.Clean(extPath)
 	switch {
 	case extPath == "~":
 		return homeDirAbsPath, nil
diff --git a/internal/cmd/testdata/scripts/issue3374.txtar b/internal/cmd/testdata/scripts/issue3374.txtar
new file mode 100644
index 00000000000..8bf342d59c3
--- /dev/null
+++ b/internal/cmd/testdata/scripts/issue3374.txtar
@@ -0,0 +1,8 @@
+# test that chezmoi copes with extra slashes in path arguments
+exec chezmoi cat $HOME//.file
+cmp stdout golden/.file
+
+-- golden/.file --
+# contents of .file
+-- home/user/.local/share/chezmoi/dot_file --
+# contents of .file