diff --git a/internal/lefthook/runner/exec/execute_unix.go b/internal/lefthook/runner/exec/execute_unix.go
index 45efaab0..32287977 100644
--- a/internal/lefthook/runner/exec/execute_unix.go
+++ b/internal/lefthook/runner/exec/execute_unix.go
@@ -10,7 +10,6 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
-	"strings"
 
 	"github.com/creack/pty"
 	"github.com/mattn/go-isatty"
@@ -44,7 +43,7 @@ func (e CommandExecutor) Execute(ctx context.Context, opts Options, in io.Reader
 	for name, value := range opts.Env {
 		envs = append(
 			envs,
-			fmt.Sprintf("%s=%s", strings.ToUpper(name), os.ExpandEnv(value)),
+			fmt.Sprintf("%s=%s", name, os.ExpandEnv(value)),
 		)
 	}
 	switch log.Colors() {
diff --git a/internal/lefthook/runner/exec/execute_windows.go b/internal/lefthook/runner/exec/execute_windows.go
index 47d72757..ce69cbf8 100644
--- a/internal/lefthook/runner/exec/execute_windows.go
+++ b/internal/lefthook/runner/exec/execute_windows.go
@@ -40,7 +40,7 @@ func (e CommandExecutor) Execute(ctx context.Context, opts Options, in io.Reader
 	for name, value := range opts.Env {
 		envs = append(
 			envs,
-			fmt.Sprintf("%s=%s", strings.ToUpper(name), os.ExpandEnv(value)),
+			fmt.Sprintf("%s=%s", name, os.ExpandEnv(value)),
 		)
 	}
 	switch log.Colors() {