diff --git a/provider/env/env.go b/provider/env/env.go
index 9d1e2ae3..deec75fc 100644
--- a/provider/env/env.go
+++ b/provider/env/env.go
@@ -48,7 +48,10 @@ func (e Env) Load() (map[string]any, error) {
 				// The environment variable with empty value is treated as unset.
 				continue
 			}
-			maps.Insert(values, e.splitter(key), value)
+
+			if keys := e.splitter(key); len(keys) > 1 || len(keys) == 1 && keys[0] != "" {
+				maps.Insert(values, keys, value)
+			}
 		}
 	}
 
diff --git a/provider/env/env_test.go b/provider/env/env_test.go
index 1a986350..e838a050 100644
--- a/provider/env/env_test.go
+++ b/provider/env/env_test.go
@@ -42,6 +42,22 @@ func TestEnv_Load(t *testing.T) {
 				},
 			},
 		},
+		{
+			description: "with nil splitter",
+			opts: []env.Option{
+				env.WithPrefix("P."),
+				env.WithNameSplitter(func(string) []string { return nil }),
+			},
+			expected: map[string]any{},
+		},
+		{
+			description: "with empty splitter",
+			opts: []env.Option{
+				env.WithPrefix("P."),
+				env.WithNameSplitter(func(string) []string { return []string{""} }),
+			},
+			expected: map[string]any{},
+		},
 	}
 
 	t.Setenv("P_K", "v")
diff --git a/provider/env/option.go b/provider/env/option.go
index a5a6bc82..cf341e41 100644
--- a/provider/env/option.go
+++ b/provider/env/option.go
@@ -31,6 +31,7 @@ func WithDelimiter(delimiter string) Option {
 }
 
 // WithNameSplitter provides the function used to split environment variable names into nested keys.
+// If it returns an nil/[]string{}/[]string{""}, the variable will be ignored.
 //
 // For example, with the default splitter, an environment variable name like "PARENT_CHILD_KEY"
 // would be split into "PARENT", "CHILD", and "KEY".
diff --git a/provider/flag/flag.go b/provider/flag/flag.go
index 4376f095..2fd73b4e 100644
--- a/provider/flag/flag.go
+++ b/provider/flag/flag.go
@@ -73,6 +73,10 @@ func (f Flag) Load() (map[string]any, error) {
 		}
 
 		keys := f.splitter(flag.Name)
+		if len(keys) == 0 || len(keys) == 1 && keys[0] == "" {
+			return
+		}
+
 		val := flag.Value.String()
 		// Skip zero default value to avoid overriding values set by other loader.
 		if val == flag.DefValue && (f.konf.Exists(keys) || isZeroDefValue(flag)) {
diff --git a/provider/flag/flag_test.go b/provider/flag/flag_test.go
index 47881259..3d64d9a9 100644
--- a/provider/flag/flag_test.go
+++ b/provider/flag/flag_test.go
@@ -52,6 +52,22 @@ func TestFlag_Load(t *testing.T) {
 				},
 			},
 		},
+		{
+			description: "with nil splitter",
+			opts: []kflag.Option{
+				kflag.WithPrefix("p_"),
+				kflag.WithNameSplitter(func(string) []string { return nil }),
+			},
+			expected: map[string]any{},
+		},
+		{
+			description: "with empty splitter",
+			opts: []kflag.Option{
+				kflag.WithPrefix("p_"),
+				kflag.WithNameSplitter(func(string) []string { return []string{""} }),
+			},
+			expected: map[string]any{},
+		},
 		{
 			description: "with prefix",
 			opts:        []kflag.Option{kflag.WithPrefix("p.")},
diff --git a/provider/flag/option.go b/provider/flag/option.go
index 137f564b..2514c452 100644
--- a/provider/flag/option.go
+++ b/provider/flag/option.go
@@ -43,6 +43,7 @@ func WithDelimiter(delimiter string) Option {
 }
 
 // WithNameSplitter provides the function used to split environment variable names into nested keys.
+// If it returns an nil/[]string{}/[]string{""}, the variable will be ignored.
 //
 // For example, with the default splitter, an flag name like "parent.child.key"
 // would be split into "parent", "child", and "key".
diff --git a/provider/pflag/option.go b/provider/pflag/option.go
index e0fc5fff..3ad4a9b2 100644
--- a/provider/pflag/option.go
+++ b/provider/pflag/option.go
@@ -44,6 +44,7 @@ func WithDelimiter(delimiter string) Option {
 }
 
 // WithNameSplitter provides the function used to split environment variable names into nested keys.
+// If it returns an nil/[]string{}/[]string{""}, the variable will be ignored.
 //
 // For example, with the default splitter, an flag name like "parent.child.key"
 // // would be split into "parent", "child", and "key".
diff --git a/provider/pflag/pflag.go b/provider/pflag/pflag.go
index d84ac952..b278bc70 100644
--- a/provider/pflag/pflag.go
+++ b/provider/pflag/pflag.go
@@ -77,6 +77,10 @@ func (f PFlag) Load() (map[string]any, error) {
 			}
 
 			keys := f.splitter(flag.Name)
+			if len(keys) == 0 || len(keys) == 1 && keys[0] == "" {
+				return
+			}
+
 			val := f.flagVal(flag)
 			// Skip zero default value to avoid overriding values set by other loader.
 			if !flag.Changed && (f.konf.Exists(keys) || reflect.ValueOf(val).IsZero()) {
diff --git a/provider/pflag/pflag_test.go b/provider/pflag/pflag_test.go
index eeba96a1..22aee58a 100644
--- a/provider/pflag/pflag_test.go
+++ b/provider/pflag/pflag_test.go
@@ -56,6 +56,22 @@ func TestPFlag_Load(t *testing.T) {
 				},
 			},
 		},
+		{
+			description: "with nil splitter",
+			opts: []kflag.Option{
+				kflag.WithPrefix("p_"),
+				kflag.WithNameSplitter(func(string) []string { return nil }),
+			},
+			expected: map[string]any{},
+		},
+		{
+			description: "with empty splitter",
+			opts: []kflag.Option{
+				kflag.WithPrefix("p_"),
+				kflag.WithNameSplitter(func(string) []string { return []string{""} }),
+			},
+			expected: map[string]any{},
+		},
 		{
 			description: "with prefix",
 			opts:        []kflag.Option{kflag.WithPrefix("p.")},