diff --git a/env/config.go b/env/config.go
index 2c94d8e..628b2fc 100644
--- a/env/config.go
+++ b/env/config.go
@@ -40,10 +40,11 @@ func (c *VarNameConstructor) setReplacement(oldChar, newChar string) {
 }
 
 func (c *VarNameConstructor) VarFromFlagName(name string) string {
-	varName := strings.ReplaceAll(name, c.varNameReplacement.old, c.varNameReplacement.new)
+	varName := name
 	if c.prefix != "" {
 		varName = fmt.Sprintf("%s_%s", c.prefix, varName)
 	}
+	varName = strings.ReplaceAll(varName, c.varNameReplacement.old, c.varNameReplacement.new)
 	if c.capitalize {
 		varName = strings.ToUpper(varName)
 	}
diff --git a/flag/flag_test.go b/flag/flag_test.go
index 6531ef2..74cd246 100644
--- a/flag/flag_test.go
+++ b/flag/flag_test.go
@@ -94,7 +94,7 @@ func assertFlag[T any](t *testing.T, f flagPropertyGetter, tt flagTest) {
 	assert.Equal(t, tt.expected.Shared(), f.IsShared())
 }
 
-func assertGetFlag[T any](t *testing.T, f flagPropertyGetter, tt getFlagTest[T]) {
+func assertGetFlagCmd[T any](t *testing.T, f flagPropertyGetter, tt getFlagTest[T]) {
 	assert.NotNil(t, f)
 	if tt.input != nil {
 		if tt.wanted.err {
@@ -108,6 +108,24 @@ func assertGetFlag[T any](t *testing.T, f flagPropertyGetter, tt getFlagTest[T])
 	assert.Equal(t, tt.wanted.some, PtrOrDie[T](f.Value()))
 }
 
+func assertGetFlagEnv[T any](t *testing.T, f flagPropertyGetter, tt getFlagTest[T]) {
+	assert.NotNil(t, f)
+	if tt.input != nil {
+		if tt.wanted.err {
+			assert.Error(t, f.FromEnvVariable(*tt.input))
+			return
+		}
+		if *tt.input == "" {
+			assert.Error(t, f.FromEnvVariable(*tt.input))
+			return
+		}
+		assert.NoError(t, f.FromEnvVariable(*tt.input))
+		assert.True(t, f.IsSetFromCmd())
+	}
+	assert.Equal(t, *tt.wanted.some, DerefOrDie[T](f.Value()))
+	assert.Equal(t, tt.wanted.some, PtrOrDie[T](f.Value()))
+}
+
 type custom struct {
 	field int
 }
@@ -128,8 +146,12 @@ func (p *customParser) ParseCmd(s string) (any, error) {
 	return &custom{field: v}, nil
 }
 
-func (p *customParser) ParseEnv(_ string) (any, error) {
-	return nil, nil
+func (p *customParser) ParseEnv(s string) (any, error) {
+	v, err := strconv.Atoi(s)
+	if err != nil {
+		return nil, err
+	}
+	return &custom{field: v}, nil
 }
 
 func TestFlag_Custom(t *testing.T) {
@@ -186,7 +208,8 @@ func TestFlag_GetCustom(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Typed[custom](tt.name, tt.opts...)
-			assertGetFlag[custom](t, f, tt)
+			assertGetFlagCmd[custom](t, f, tt)
+			assertGetFlagEnv[custom](t, f, tt)
 		})
 	}
 }
@@ -265,7 +288,8 @@ func TestFlag_GetString(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := String(tt.name, tt.opts...)
-			assertGetFlag[string](t, f, tt)
+			assertGetFlagCmd[string](t, f, tt)
+			assertGetFlagEnv[string](t, f, tt)
 		})
 	}
 }
@@ -353,7 +377,8 @@ func TestFlag_GetDuration(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Duration(tt.name, tt.opts...)
-			assertGetFlag[time.Duration](t, f, tt)
+			assertGetFlagCmd[time.Duration](t, f, tt)
+			assertGetFlagEnv[time.Duration](t, f, tt)
 		})
 	}
 }
@@ -450,7 +475,8 @@ func TestFlag_GetBool(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Bool(tt.name, tt.opts...)
-			assertGetFlag[bool](t, f, tt)
+			assertGetFlagCmd[bool](t, f, tt)
+			assertGetFlagEnv[bool](t, f, tt)
 		})
 	}
 }
@@ -526,7 +552,8 @@ func TestFlag_GetInt(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Int(tt.name, tt.opts...)
-			assertGetFlag[int](t, f, tt)
+			assertGetFlagCmd[int](t, f, tt)
+			assertGetFlagEnv[int](t, f, tt)
 		})
 	}
 }
@@ -602,7 +629,8 @@ func TestFlag_GetInt8(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Int8(tt.name, tt.opts...)
-			assertGetFlag[int8](t, f, tt)
+			assertGetFlagCmd[int8](t, f, tt)
+			assertGetFlagEnv[int8](t, f, tt)
 		})
 	}
 }
@@ -678,7 +706,8 @@ func TestFlag_GetInt16(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Int16(tt.name, tt.opts...)
-			assertGetFlag[int16](t, f, tt)
+			assertGetFlagCmd[int16](t, f, tt)
+			assertGetFlagEnv[int16](t, f, tt)
 		})
 	}
 }
@@ -754,7 +783,8 @@ func TestFlag_GetInt32(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Int32(tt.name, tt.opts...)
-			assertGetFlag[int32](t, f, tt)
+			assertGetFlagCmd[int32](t, f, tt)
+			assertGetFlagEnv[int32](t, f, tt)
 		})
 	}
 }
@@ -830,7 +860,8 @@ func TestFlag_GetInt64(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Int64(tt.name, tt.opts...)
-			assertGetFlag[int64](t, f, tt)
+			assertGetFlagCmd[int64](t, f, tt)
+			assertGetFlagEnv[int64](t, f, tt)
 		})
 	}
 }
@@ -906,7 +937,8 @@ func TestFlag_GetUint(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Uint(tt.name, tt.opts...)
-			assertGetFlag[uint](t, f, tt)
+			assertGetFlagCmd[uint](t, f, tt)
+			assertGetFlagEnv[uint](t, f, tt)
 		})
 	}
 }
@@ -982,7 +1014,8 @@ func TestFlag_GetUint8(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Uint8(tt.name, tt.opts...)
-			assertGetFlag[uint8](t, f, tt)
+			assertGetFlagCmd[uint8](t, f, tt)
+			assertGetFlagEnv[uint8](t, f, tt)
 		})
 	}
 }
@@ -1058,7 +1091,8 @@ func TestFlag_GetUint16(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Uint16(tt.name, tt.opts...)
-			assertGetFlag[uint16](t, f, tt)
+			assertGetFlagCmd[uint16](t, f, tt)
+			assertGetFlagEnv[uint16](t, f, tt)
 		})
 	}
 }
@@ -1134,7 +1168,8 @@ func TestFlag_GetUint32(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Uint32(tt.name, tt.opts...)
-			assertGetFlag[uint32](t, f, tt)
+			assertGetFlagCmd[uint32](t, f, tt)
+			assertGetFlagEnv[uint32](t, f, tt)
 		})
 	}
 }
@@ -1210,7 +1245,8 @@ func TestFlag_GetUint64(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Uint64(tt.name, tt.opts...)
-			assertGetFlag[uint64](t, f, tt)
+			assertGetFlagCmd[uint64](t, f, tt)
+			assertGetFlagEnv[uint64](t, f, tt)
 		})
 	}
 }
@@ -1286,7 +1322,8 @@ func TestFlag_GetFloat32(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Float32(tt.name, tt.opts...)
-			assertGetFlag[float32](t, f, tt)
+			assertGetFlagCmd[float32](t, f, tt)
+			assertGetFlagEnv[float32](t, f, tt)
 		})
 	}
 }
@@ -1362,7 +1399,8 @@ func TestFlag_GetFloat64(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Float64(tt.name, tt.opts...)
-			assertGetFlag[float64](t, f, tt)
+			assertGetFlagCmd[float64](t, f, tt)
+			assertGetFlagEnv[float64](t, f, tt)
 		})
 	}
 }
@@ -1449,7 +1487,8 @@ func TestFlag_GetIntSlice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := IntSlice(tt.name, tt.opts...)
-			assertGetFlag[[]int](t, f, tt)
+			assertGetFlagCmd[[]int](t, f, tt)
+			assertGetFlagEnv[[]int](t, f, tt)
 		})
 	}
 }
@@ -1536,7 +1575,8 @@ func TestFlag_GetInt8Slice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Int8Slice(tt.name, tt.opts...)
-			assertGetFlag[[]int8](t, f, tt)
+			assertGetFlagCmd[[]int8](t, f, tt)
+			assertGetFlagEnv[[]int8](t, f, tt)
 		})
 	}
 }
@@ -1623,7 +1663,8 @@ func TestFlag_GetInt16Slice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Int16Slice(tt.name, tt.opts...)
-			assertGetFlag[[]int16](t, f, tt)
+			assertGetFlagCmd[[]int16](t, f, tt)
+			assertGetFlagEnv[[]int16](t, f, tt)
 		})
 	}
 }
@@ -1710,7 +1751,8 @@ func TestFlag_GetInt32Slice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Int32Slice(tt.name, tt.opts...)
-			assertGetFlag[[]int32](t, f, tt)
+			assertGetFlagCmd[[]int32](t, f, tt)
+			assertGetFlagEnv[[]int32](t, f, tt)
 		})
 	}
 }
@@ -1797,7 +1839,8 @@ func TestFlag_GetInt64Slice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Int64Slice(tt.name, tt.opts...)
-			assertGetFlag[[]int64](t, f, tt)
+			assertGetFlagCmd[[]int64](t, f, tt)
+			assertGetFlagEnv[[]int64](t, f, tt)
 		})
 	}
 }
@@ -1884,7 +1927,8 @@ func TestFlag_GetUintSlice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := UintSlice(tt.name, tt.opts...)
-			assertGetFlag[[]uint](t, f, tt)
+			assertGetFlagCmd[[]uint](t, f, tt)
+			assertGetFlagEnv[[]uint](t, f, tt)
 		})
 	}
 }
@@ -1971,7 +2015,8 @@ func TestFlag_GetUint8Slice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Uint8Slice(tt.name, tt.opts...)
-			assertGetFlag[[]uint8](t, f, tt)
+			assertGetFlagCmd[[]uint8](t, f, tt)
+			assertGetFlagEnv[[]uint8](t, f, tt)
 		})
 	}
 }
@@ -2058,7 +2103,8 @@ func TestFlag_GetUint16Slice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Uint16Slice(tt.name, tt.opts...)
-			assertGetFlag[[]uint16](t, f, tt)
+			assertGetFlagCmd[[]uint16](t, f, tt)
+			assertGetFlagEnv[[]uint16](t, f, tt)
 		})
 	}
 }
@@ -2145,7 +2191,8 @@ func TestFlag_GetUint32Slice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Uint32Slice(tt.name, tt.opts...)
-			assertGetFlag[[]uint32](t, f, tt)
+			assertGetFlagCmd[[]uint32](t, f, tt)
+			assertGetFlagEnv[[]uint32](t, f, tt)
 		})
 	}
 }
@@ -2232,7 +2279,8 @@ func TestFlag_GetUint64Slice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Uint64Slice(tt.name, tt.opts...)
-			assertGetFlag[[]uint64](t, f, tt)
+			assertGetFlagCmd[[]uint64](t, f, tt)
+			assertGetFlagEnv[[]uint64](t, f, tt)
 		})
 	}
 }
@@ -2319,7 +2367,8 @@ func TestFlag_GetFloat32Slice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Float32Slice(tt.name, tt.opts...)
-			assertGetFlag[[]float32](t, f, tt)
+			assertGetFlagCmd[[]float32](t, f, tt)
+			assertGetFlagEnv[[]float32](t, f, tt)
 		})
 	}
 }
@@ -2406,7 +2455,8 @@ func TestFlag_GetFloat64Slice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Float64Slice(tt.name, tt.opts...)
-			assertGetFlag[[]float64](t, f, tt)
+			assertGetFlagCmd[[]float64](t, f, tt)
+			assertGetFlagEnv[[]float64](t, f, tt)
 		})
 	}
 }
@@ -2484,7 +2534,8 @@ func TestFlag_GetStringSlice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := StringSlice(tt.name, tt.opts...)
-			assertGetFlag[[]string](t, f, tt)
+			assertGetFlagCmd[[]string](t, f, tt)
+			assertGetFlagEnv[[]string](t, f, tt)
 		})
 	}
 }
@@ -2571,7 +2622,8 @@ func TestFlag_GetDurationSlice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := DurationSlice(tt.name, tt.opts...)
-			assertGetFlag[[]time.Duration](t, f, tt)
+			assertGetFlagCmd[[]time.Duration](t, f, tt)
+			assertGetFlagEnv[[]time.Duration](t, f, tt)
 		})
 	}
 }
@@ -2658,7 +2710,8 @@ func TestFlag_GetBoolSlice(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := BoolSlice(tt.name, tt.opts...)
-			assertGetFlag[[]bool](t, f, tt)
+			assertGetFlagCmd[[]bool](t, f, tt)
+			assertGetFlagEnv[[]bool](t, f, tt)
 		})
 	}
 }
@@ -2737,7 +2790,8 @@ func TestFlag_GetCounter(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			f := Counter(tt.name, tt.opts...)
-			assertGetFlag[int](t, f, tt)
+			assertGetFlagCmd[int](t, f, tt)
+			assertGetFlagEnv[int](t, f, tt)
 		})
 	}
 }
diff --git a/flagset/flagset_test.go b/flagset/flagset_test.go
index 055236e..7c7abb7 100644
--- a/flagset/flagset_test.go
+++ b/flagset/flagset_test.go
@@ -677,18 +677,27 @@ func TestFlagSet_BindEnvVars(t *testing.T) {
 				fs := New(env.Prefix("test1"), env.Capitalized(), env.VarNameReplace("-", "_")).
 					BindFlag(flag.String("sample-string")).
 					BindFlag(flag.Bool("sample-bool")).
+					BindFlag(flag.Counter("sample-counter")).
+					BindFlag(flag.Float32("sample-float32")).
+					BindFlag(flag.Float64("sample-float64")).
 					BindFlag(flag.Duration("sample-duration")).Build()
 				return fs
 			},
 			variables: map[string]string{
 				"TEST1_SAMPLE_STRING":   "foo",
 				"TEST1_SAMPLE_BOOL":     "true",
+				"TEST1_SAMPLE_COUNTER":  "1",
+				"TEST1_SAMPLE_FLOAT32":  "3.14",
+				"TEST1_SAMPLE_FLOAT64":  "3.14",
 				"TEST1_SAMPLE_DURATION": "15m",
 			},
 			expected: expected{
 				parsed: []result{
 					{flagName: "sample-duration", flagValue: time.Minute * 15, flagType: "duration"},
 					{flagName: "sample-string", flagValue: "foo", flagType: "string"},
+					{flagName: "sample-counter", flagValue: 1, flagType: "counter"},
+					{flagName: "sample-float32", flagValue: float32(3.14), flagType: "float32"},
+					{flagName: "sample-float64", flagValue: 3.14, flagType: "float64"},
 					{flagName: "sample-bool", flagValue: true, flagType: "bool"},
 				},
 				err: false,
@@ -700,20 +709,285 @@ func TestFlagSet_BindEnvVars(t *testing.T) {
 				fs := New(env.Prefix("test2"), env.Capitalized(), env.VarNameReplace("-", "_")).
 					BindFlag(flag.String("sample-string")).
 					BindFlag(flag.Bool("sample-bool")).
+					BindFlag(flag.Counter("sample-counter")).
+					BindFlag(flag.Float32("sample-float32")).
+					BindFlag(flag.Float64("sample-float64")).
 					BindFlag(flag.Duration("sample-duration")).Build()
 				return fs
 			},
 			variables: map[string]string{
 				"TEST2_SAMPLE_STRING":   "foo",
 				"TEST2_SAMPLE_BOOL":     "yes",
+				"TEST2_SAMPLE_COUNTER":  "one",
+				"TEST2_SAMPLE_FLOAT32":  "3.4e+39",
+				"TEST2_SAMPLE_FLOAT64":  "1.7e+308",
 				"TEST2_SAMPLE_DURATION": "15m",
 			},
+			expected: expected{
+				parsed:      []result{},
+				err:         true,
+				expectedErr: ferrors.ErrParseFailed,
+			},
+		},
+		{
+			name: "env vars slices success",
+			flagSet: func() *FlagSet {
+				fs := New(env.Prefix("test1-slice"), env.Capitalized(), env.VarNameReplace("-", "_")).
+					BindFlag(flag.StringSlice("sample-string")).
+					BindFlag(flag.BoolSlice("sample-bool")).
+					BindFlag(flag.Float32Slice("sample-float32")).
+					BindFlag(flag.Float64Slice("sample-float64")).
+					BindFlag(flag.DurationSlice("sample-duration")).Build()
+				return fs
+			},
+			variables: map[string]string{
+				"TEST1_SLICE_SAMPLE_STRING":   "foo",
+				"TEST1_SLICE_SAMPLE_BOOL":     "true",
+				"TEST1_SLICE_SAMPLE_FLOAT32":  "3.14",
+				"TEST1_SLICE_SAMPLE_FLOAT64":  "3.14",
+				"TEST1_SLICE_SAMPLE_DURATION": "15m",
+			},
 			expected: expected{
 				parsed: []result{
-					{flagName: "sample-duration", flagValue: time.Minute * 15, flagType: "duration"},
-					{flagName: "sample-string", flagValue: "foo", flagType: "string"},
-					{flagName: "sample-bool", flagValue: true, flagType: "bool"},
+					{flagName: "sample-duration", flagValue: []time.Duration{time.Minute * 15}, flagType: "durationSlice"},
+					{flagName: "sample-string", flagValue: []string{"foo"}, flagType: "stringSlice"},
+					{flagName: "sample-float32", flagValue: []float32{3.14}, flagType: "float32slice"},
+					{flagName: "sample-float64", flagValue: []float64{3.14}, flagType: "float64slice"},
+					{flagName: "sample-bool", flagValue: []bool{true}, flagType: "boolSlice"},
 				},
+				err: false,
+			},
+		},
+		{
+			name: "env vars slices failed",
+			flagSet: func() *FlagSet {
+				fs := New(env.Prefix("test2-slice"), env.Capitalized(), env.VarNameReplace("-", "_")).
+					BindFlag(flag.BoolSlice("sample-bool")).
+					BindFlag(flag.Float32Slice("sample-float32")).
+					BindFlag(flag.Float64Slice("sample-float64")).
+					BindFlag(flag.DurationSlice("sample-duration")).Build()
+				return fs
+			},
+			variables: map[string]string{
+				"TEST2_SLICE_SAMPLE_BOOL":     "yes",
+				"TEST2_SLICE_SAMPLE_FLOAT32":  "3.4e+39",
+				"TEST2_SLICE_SAMPLE_FLOAT64":  "1.7e+308",
+				"TEST2_SLICE_SAMPLE_DURATION": "15m",
+			},
+			expected: expected{
+				parsed:      []result{},
+				err:         true,
+				expectedErr: ferrors.ErrParseFailed,
+			},
+		},
+		{
+			name: "env vars signed integers success",
+			flagSet: func() *FlagSet {
+				fs := New(env.Prefix("integers-success"), env.Capitalized(), env.VarNameReplace("-", "_")).
+					BindFlag(flag.Int("sample-int")).
+					BindFlag(flag.Int8("sample-int8")).
+					BindFlag(flag.Int16("sample-int16")).
+					BindFlag(flag.Int32("sample-int32")).
+					BindFlag(flag.Int64("sample-int64")).Build()
+				return fs
+			},
+			variables: map[string]string{
+				"INTEGERS_SUCCESS_SAMPLE_INT":   "42",
+				"INTEGERS_SUCCESS_SAMPLE_INT8":  "42",
+				"INTEGERS_SUCCESS_SAMPLE_INT16": "42",
+				"INTEGERS_SUCCESS_SAMPLE_INT32": "42",
+				"INTEGERS_SUCCESS_SAMPLE_INT64": "42",
+			},
+			expected: expected{
+				parsed: []result{
+					{flagName: "sample-int", flagValue: 42, flagType: "int"},
+					{flagName: "sample-int8", flagValue: int8(42), flagType: "int8"},
+					{flagName: "sample-int16", flagValue: int16(42), flagType: "int16"},
+					{flagName: "sample-int32", flagValue: int32(42), flagType: "int32"},
+					{flagName: "sample-int64", flagValue: int64(42), flagType: "int64"},
+				},
+				err: false,
+			},
+		},
+		{
+			name: "env vars signed integers failure",
+			flagSet: func() *FlagSet {
+				fs := New(env.Prefix("integers-fail"), env.Capitalized(), env.VarNameReplace("-", "_")).
+					BindFlag(flag.Int("sample-int")).
+					BindFlag(flag.Int8("sample-int8")).
+					BindFlag(flag.Int16("sample-int16")).
+					BindFlag(flag.Int32("sample-int32")).
+					BindFlag(flag.Int64("sample-int64")).Build()
+				return fs
+			},
+			variables: map[string]string{
+				"INTEGERS_FAIL_SAMPLE_INT":   "42.",
+				"INTEGERS_FAIL_SAMPLE_INT8":  "1000",
+				"INTEGERS_FAIL_SAMPLE_INT16": "-32800",
+				"INTEGERS_FAIL_SAMPLE_INT32": "65656",
+				"INTEGERS_FAIL_SAMPLE_INT64": "9223372036854775809",
+			},
+			expected: expected{
+				parsed:      []result{},
+				err:         true,
+				expectedErr: ferrors.ErrParseFailed,
+			},
+		},
+		{
+			name: "env vars unsigned integers success",
+			flagSet: func() *FlagSet {
+				fs := New(env.Prefix("uintegers-success"), env.Capitalized(), env.VarNameReplace("-", "_")).
+					BindFlag(flag.Uint("sample-uint")).
+					BindFlag(flag.Uint8("sample-uint8")).
+					BindFlag(flag.Uint16("sample-uint16")).
+					BindFlag(flag.Uint32("sample-uint32")).
+					BindFlag(flag.Uint64("sample-uint64")).Build()
+				return fs
+			},
+			variables: map[string]string{
+				"UINTEGERS_SUCCESS_SAMPLE_UINT":   "42",
+				"UINTEGERS_SUCCESS_SAMPLE_UINT8":  "42",
+				"UINTEGERS_SUCCESS_SAMPLE_UINT16": "42",
+				"UINTEGERS_SUCCESS_SAMPLE_UINT32": "42",
+				"UINTEGERS_SUCCESS_SAMPLE_UINT64": "42",
+			},
+			expected: expected{
+				parsed: []result{
+					{flagName: "sample-uint", flagValue: uint(42), flagType: "uint"},
+					{flagName: "sample-uint8", flagValue: uint8(42), flagType: "uint8"},
+					{flagName: "sample-uint16", flagValue: uint16(42), flagType: "uint16"},
+					{flagName: "sample-uint32", flagValue: uint32(42), flagType: "uint32"},
+					{flagName: "sample-uint64", flagValue: uint64(42), flagType: "uint64"},
+				},
+				err: false,
+			},
+		},
+		{
+			name: "env vars signed uintegers failure",
+			flagSet: func() *FlagSet {
+				fs := New(env.Prefix("uintegers-fail"), env.Capitalized(), env.VarNameReplace("-", "_")).
+					BindFlag(flag.Uint("sample-uint")).
+					BindFlag(flag.Uint8("sample-uint8")).
+					BindFlag(flag.Uint16("sample-uint16")).
+					BindFlag(flag.Uint32("sample-uint32")).
+					BindFlag(flag.Uint64("sample-uint64")).Build()
+				return fs
+			},
+			variables: map[string]string{
+				"UINTEGERS_FAIL_SAMPLE_UINT":   "42.",
+				"UINTEGERS_FAIL_SAMPLE_UINT8":  "1000",
+				"UINTEGERS_FAIL_SAMPLE_UINT16": "-32800",
+				"UINTEGERS_FAIL_SAMPLE_UINT32": "-165656",
+				"UINTEGERS_FAIL_SAMPLE_UINT64": "184467440737095516150",
+			},
+			expected: expected{
+				parsed:      []result{},
+				err:         true,
+				expectedErr: ferrors.ErrParseFailed,
+			},
+		},
+		{
+			name: "env vars signed integers slices success",
+			flagSet: func() *FlagSet {
+				fs := New(env.Prefix("integers-slice-success"), env.Capitalized(), env.VarNameReplace("-", "_")).
+					BindFlag(flag.IntSlice("sample-int")).
+					BindFlag(flag.Int8Slice("sample-int8")).
+					BindFlag(flag.Int16Slice("sample-int16")).
+					BindFlag(flag.Int32Slice("sample-int32")).
+					BindFlag(flag.Int64Slice("sample-int64")).Build()
+				return fs
+			},
+			variables: map[string]string{
+				"INTEGERS_SLICE_SUCCESS_SAMPLE_INT":   "42",
+				"INTEGERS_SLICE_SUCCESS_SAMPLE_INT8":  "42",
+				"INTEGERS_SLICE_SUCCESS_SAMPLE_INT16": "42",
+				"INTEGERS_SLICE_SUCCESS_SAMPLE_INT32": "42",
+				"INTEGERS_SLICE_SUCCESS_SAMPLE_INT64": "42",
+			},
+			expected: expected{
+				parsed: []result{
+					{flagName: "sample-int", flagValue: []int{42}, flagType: "intSlice"},
+					{flagName: "sample-int8", flagValue: []int8{42}, flagType: "int8slice"},
+					{flagName: "sample-int16", flagValue: []int16{42}, flagType: "int16slice"},
+					{flagName: "sample-int32", flagValue: []int32{42}, flagType: "int32slice"},
+					{flagName: "sample-int64", flagValue: []int64{42}, flagType: "int64slice"},
+				},
+				err: false,
+			},
+		},
+		{
+			name: "env vars signed integers slices failure",
+			flagSet: func() *FlagSet {
+				fs := New(env.Prefix("integers-slice-failure"), env.Capitalized(), env.VarNameReplace("-", "_")).
+					BindFlag(flag.IntSlice("sample-int")).
+					BindFlag(flag.Int8Slice("sample-int8")).
+					BindFlag(flag.Int16Slice("sample-int16")).
+					BindFlag(flag.Int32Slice("sample-int32")).
+					BindFlag(flag.Int64Slice("sample-int64")).Build()
+				return fs
+			},
+			variables: map[string]string{
+				"INTEGERS_SLICE_FAILURE_SAMPLE_INT":   "42.",
+				"INTEGERS_SLICE_FAILURE_SAMPLE_INT8":  "1000",
+				"INTEGERS_SLICE_FAILURE_SAMPLE_INT16": "-32800",
+				"INTEGERS_SLICE_FAILURE_SAMPLE_INT32": "65656",
+				"INTEGERS_SLICE_FAILURE_SAMPLE_INT64": "18446744073709551615",
+			},
+			expected: expected{
+				parsed:      []result{},
+				err:         true,
+				expectedErr: ferrors.ErrParseFailed,
+			},
+		},
+		{
+			name: "env vars unsigned integers slices success",
+			flagSet: func() *FlagSet {
+				fs := New(env.Prefix("uintegers-slice-success"), env.Capitalized(), env.VarNameReplace("-", "_")).
+					BindFlag(flag.UintSlice("sample-uint")).
+					BindFlag(flag.Uint8Slice("sample-uint8")).
+					BindFlag(flag.Uint16Slice("sample-uint16")).
+					BindFlag(flag.Uint32Slice("sample-uint32")).
+					BindFlag(flag.Uint64Slice("sample-uint64")).Build()
+				return fs
+			},
+			variables: map[string]string{
+				"UINTEGERS_SLICE_SUCCESS_SAMPLE_UINT":   "42",
+				"UINTEGERS_SLICE_SUCCESS_SAMPLE_UINT8":  "42",
+				"UINTEGERS_SLICE_SUCCESS_SAMPLE_UINT16": "42",
+				"UINTEGERS_SLICE_SUCCESS_SAMPLE_UINT32": "42",
+				"UINTEGERS_SLICE_SUCCESS_SAMPLE_UINT64": "42",
+			},
+			expected: expected{
+				parsed: []result{
+					{flagName: "sample-uint", flagValue: []uint{42}, flagType: "uintSlice"},
+					{flagName: "sample-uint8", flagValue: []uint8{42}, flagType: "uint8slice"},
+					{flagName: "sample-uint16", flagValue: []uint16{42}, flagType: "uint16slice"},
+					{flagName: "sample-uint32", flagValue: []uint32{42}, flagType: "uint32slice"},
+					{flagName: "sample-uint64", flagValue: []uint64{42}, flagType: "uint64slice"},
+				},
+				err: false,
+			},
+		},
+		{
+			name: "env vars unsigned integers slices failure",
+			flagSet: func() *FlagSet {
+				fs := New(env.Prefix("uintegers-slice-failure"), env.Capitalized(), env.VarNameReplace("-", "_")).
+					BindFlag(flag.IntSlice("sample-uint")).
+					BindFlag(flag.Int8Slice("sample-uint8")).
+					BindFlag(flag.Int16Slice("sample-uint16")).
+					BindFlag(flag.Int32Slice("sample-uint32")).
+					BindFlag(flag.Int64Slice("sample-uint64")).Build()
+				return fs
+			},
+			variables: map[string]string{
+				"UINTEGERS_SLICE_FAILURE_SAMPLE_UINT":   "42.",
+				"UINTEGERS_SLICE_FAILURE_SAMPLE_UINT8":  "1000",
+				"UINTEGERS_SLICE_FAILURE_SAMPLE_UINT16": "-32800",
+				"UINTEGERS_SLICE_FAILURE_SAMPLE_UINT32": "-65656",
+				"UINTEGERS_SLICE_FAILURE_SAMPLE_UINT64": "1018446744073709551615",
+			},
+			expected: expected{
+				parsed:      []result{},
 				err:         true,
 				expectedErr: ferrors.ErrParseFailed,
 			},