diff --git a/cast_test.go b/cast_test.go
index 8e964fb..2bb8c5f 100644
--- a/cast_test.go
+++ b/cast_test.go
@@ -37,6 +37,14 @@ func TestToUintE(t *testing.T) {
 		{"8", 8, false},
 		{nil, 0, false},
 		// errors
+		{int(-8), 0, true},
+		{int8(-8), 0, true},
+		{int16(-8), 0, true},
+		{int32(-8), 0, true},
+		{int64(-8), 0, true},
+		{float32(-8.31), 0, true},
+		{float64(-8.31), 0, true},
+		{"-8", 0, true},
 		{"test", 0, true},
 		{testing.T{}, 0, true},
 	}
@@ -82,6 +90,14 @@ func TestToUint64E(t *testing.T) {
 		{"8", 8, false},
 		{nil, 0, false},
 		// errors
+		{int(-8), 0, true},
+		{int8(-8), 0, true},
+		{int16(-8), 0, true},
+		{int32(-8), 0, true},
+		{int64(-8), 0, true},
+		{float32(-8.31), 0, true},
+		{float64(-8.31), 0, true},
+		{"-8", 0, true},
 		{"test", 0, true},
 		{testing.T{}, 0, true},
 	}
@@ -126,6 +142,14 @@ func TestToUint32E(t *testing.T) {
 		{false, 0, false},
 		{"8", 8, false},
 		{nil, 0, false},
+		{int(-8), 0, true},
+		{int8(-8), 0, true},
+		{int16(-8), 0, true},
+		{int32(-8), 0, true},
+		{int64(-8), 0, true},
+		{float32(-8.31), 0, true},
+		{float64(-8.31), 0, true},
+		{"-8", 0, true},
 		// errors
 		{"test", 0, true},
 		{testing.T{}, 0, true},
@@ -172,6 +196,14 @@ func TestToUint16E(t *testing.T) {
 		{"8", 8, false},
 		{nil, 0, false},
 		// errors
+		{int(-8), 0, true},
+		{int8(-8), 0, true},
+		{int16(-8), 0, true},
+		{int32(-8), 0, true},
+		{int64(-8), 0, true},
+		{float32(-8.31), 0, true},
+		{float64(-8.31), 0, true},
+		{"-8", 0, true},
 		{"test", 0, true},
 		{testing.T{}, 0, true},
 	}
@@ -217,6 +249,14 @@ func TestToUint8E(t *testing.T) {
 		{"8", 8, false},
 		{nil, 0, false},
 		// errors
+		{int(-8), 0, true},
+		{int8(-8), 0, true},
+		{int16(-8), 0, true},
+		{int32(-8), 0, true},
+		{int64(-8), 0, true},
+		{float32(-8.31), 0, true},
+		{float64(-8.31), 0, true},
+		{"-8", 0, true},
 		{"test", 0, true},
 		{testing.T{}, 0, true},
 	}
diff --git a/caste.go b/caste.go
index 79e6ae4..e4a25ec 100644
--- a/caste.go
+++ b/caste.go
@@ -424,14 +424,29 @@ func ToUintE(i interface{}) (uint, error) {
 		}
 		return 0, fmt.Errorf("unable to cast %#v to uint: %s", i, err)
 	case int:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint")
+		}
 		return uint(s), nil
 	case int64:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint")
+		}
 		return uint(s), nil
 	case int32:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint")
+		}
 		return uint(s), nil
 	case int16:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint")
+		}
 		return uint(s), nil
 	case int8:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint")
+		}
 		return uint(s), nil
 	case uint:
 		return s, nil
@@ -444,8 +459,14 @@ func ToUintE(i interface{}) (uint, error) {
 	case uint8:
 		return uint(s), nil
 	case float64:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint")
+		}
 		return uint(s), nil
 	case float32:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint")
+		}
 		return uint(s), nil
 	case bool:
 		if s {
@@ -471,14 +492,29 @@ func ToUint64E(i interface{}) (uint64, error) {
 		}
 		return 0, fmt.Errorf("unable to cast %#v to uint64: %s", i, err)
 	case int:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint64")
+		}
 		return uint64(s), nil
 	case int64:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint64")
+		}
 		return uint64(s), nil
 	case int32:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint64")
+		}
 		return uint64(s), nil
 	case int16:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint64")
+		}
 		return uint64(s), nil
 	case int8:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint64")
+		}
 		return uint64(s), nil
 	case uint:
 		return uint64(s), nil
@@ -491,8 +527,14 @@ func ToUint64E(i interface{}) (uint64, error) {
 	case uint8:
 		return uint64(s), nil
 	case float32:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint64")
+		}
 		return uint64(s), nil
 	case float64:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint64")
+		}
 		return uint64(s), nil
 	case bool:
 		if s {
@@ -518,14 +560,29 @@ func ToUint32E(i interface{}) (uint32, error) {
 		}
 		return 0, fmt.Errorf("unable to cast %#v to uint32: %s", i, err)
 	case int:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint32")
+		}
 		return uint32(s), nil
 	case int64:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint32")
+		}
 		return uint32(s), nil
 	case int32:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint32")
+		}
 		return uint32(s), nil
 	case int16:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint32")
+		}
 		return uint32(s), nil
 	case int8:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint32")
+		}
 		return uint32(s), nil
 	case uint:
 		return uint32(s), nil
@@ -538,8 +595,14 @@ func ToUint32E(i interface{}) (uint32, error) {
 	case uint8:
 		return uint32(s), nil
 	case float64:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint32")
+		}
 		return uint32(s), nil
 	case float32:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint32")
+		}
 		return uint32(s), nil
 	case bool:
 		if s {
@@ -565,14 +628,29 @@ func ToUint16E(i interface{}) (uint16, error) {
 		}
 		return 0, fmt.Errorf("unable to cast %#v to uint16: %s", i, err)
 	case int:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint16")
+		}
 		return uint16(s), nil
 	case int64:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint16")
+		}
 		return uint16(s), nil
 	case int32:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint16")
+		}
 		return uint16(s), nil
 	case int16:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint16")
+		}
 		return uint16(s), nil
 	case int8:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint16")
+		}
 		return uint16(s), nil
 	case uint:
 		return uint16(s), nil
@@ -585,8 +663,14 @@ func ToUint16E(i interface{}) (uint16, error) {
 	case uint8:
 		return uint16(s), nil
 	case float64:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint16")
+		}
 		return uint16(s), nil
 	case float32:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint16")
+		}
 		return uint16(s), nil
 	case bool:
 		if s {
@@ -612,14 +696,29 @@ func ToUint8E(i interface{}) (uint8, error) {
 		}
 		return 0, fmt.Errorf("unable to cast %#v to uint8: %s", i, err)
 	case int:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint8")
+		}
 		return uint8(s), nil
 	case int64:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint8")
+		}
 		return uint8(s), nil
 	case int32:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint8")
+		}
 		return uint8(s), nil
 	case int16:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint8")
+		}
 		return uint8(s), nil
 	case int8:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint8")
+		}
 		return uint8(s), nil
 	case uint:
 		return uint8(s), nil
@@ -632,8 +731,14 @@ func ToUint8E(i interface{}) (uint8, error) {
 	case uint8:
 		return s, nil
 	case float64:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint8")
+		}
 		return uint8(s), nil
 	case float32:
+		if s < 0 {
+			return 0, fmt.Errorf("unable to cast negative value to uint8")
+		}
 		return uint8(s), nil
 	case bool:
 		if s {