diff --git a/CHANGELOG.md b/CHANGELOG.md
index 375b503d..f99f9bba 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- Fixed a bug in YAML and TOML parsers that caused them to fail when parsing non-base10 numbers (e.g. hex, binary, octal).
+- Fixed a bug in the `toInt` function that caused it to fail when parsing non-base10 numbers (e.g. hex, binary, octal).
 - XML child element ordering now has more comprehensive round-trip handling. Thanks @takeokunn.
 
 ## [v3.4.1] - 2026-03-30
diff --git a/execution/func_to_int.go b/execution/func_to_int.go
index d8c38723..578d334d 100644
--- a/execution/func_to_int.go
+++ b/execution/func_to_int.go
@@ -19,7 +19,7 @@ var FuncToInt = NewFunc(
 				return nil, err
 			}
 
-			i, err := strconv.ParseInt(stringValue, 10, 64)
+			i, err := strconv.ParseInt(stringValue, 0, 64)
 			if err != nil {
 				return nil, err
 			}
diff --git a/parsing/toml/toml_reader.go b/parsing/toml/toml_reader.go
index 56f56f3e..55d3aec8 100644
--- a/parsing/toml/toml_reader.go
+++ b/parsing/toml/toml_reader.go
@@ -150,7 +150,7 @@ func (j *tomlReader) readNode(p *unstable.Parser, n *unstable.Node) (string, *mo
 		}
 		return "", model.NewFloatValue(f), nil
 	case unstable.Integer:
-		i64, err := strconv.ParseInt(string(n.Data), 10, 64)
+		i64, err := strconv.ParseInt(string(n.Data), 0, 64)
 		if err != nil {
 			return "", nil, err
 		}
diff --git a/parsing/toml/toml_reader_test.go b/parsing/toml/toml_reader_test.go
index 42ae43dc..911aa0ce 100644
--- a/parsing/toml/toml_reader_test.go
+++ b/parsing/toml/toml_reader_test.go
@@ -514,6 +514,44 @@ func TestTomlReader_EdgeCases(t *testing.T) {
 	})
 }
 
+func TestTomlReader_NonBase10Numbers(t *testing.T) {
+	t.Run("hex", tomlReaderTest([]byte(`val = 0x12`), func() *model.Value {
+		res := model.NewMapValue()
+		_ = res.SetMapKey("val", model.NewIntValue(18))
+		return res
+	}))
+
+	t.Run("octal", tomlReaderTest([]byte(`val = 0o7`), func() *model.Value {
+		res := model.NewMapValue()
+		_ = res.SetMapKey("val", model.NewIntValue(7))
+		return res
+	}))
+
+	t.Run("binary", tomlReaderTest([]byte(`val = 0b111`), func() *model.Value {
+		res := model.NewMapValue()
+		_ = res.SetMapKey("val", model.NewIntValue(7))
+		return res
+	}))
+
+	t.Run("underscore decimal", tomlReaderTest([]byte(`val = 12_000`), func() *model.Value {
+		res := model.NewMapValue()
+		_ = res.SetMapKey("val", model.NewIntValue(12000))
+		return res
+	}))
+
+	t.Run("negative underscore decimal", tomlReaderTest([]byte(`val = -12_000`), func() *model.Value {
+		res := model.NewMapValue()
+		_ = res.SetMapKey("val", model.NewIntValue(-12000))
+		return res
+	}))
+
+	t.Run("negative int", tomlReaderTest([]byte(`val = -42`), func() *model.Value {
+		res := model.NewMapValue()
+		_ = res.SetMapKey("val", model.NewIntValue(-42))
+		return res
+	}))
+}
+
 func TestTomlReader_TimeStrings(t *testing.T) {
 	// Local date
 	t.Run("local date string", func(t *testing.T) {
diff --git a/parsing/yaml/yaml_reader.go b/parsing/yaml/yaml_reader.go
index ed82d8f1..6cef7fa2 100644
--- a/parsing/yaml/yaml_reader.go
+++ b/parsing/yaml/yaml_reader.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"strconv"
+	"strings"
 
 	"github.com/tomwright/dasel/v3/model"
 	"github.com/tomwright/dasel/v3/parsing"
@@ -96,11 +97,11 @@ func (yv *yamlValue) UnmarshalYAML(value *yaml.Node) error {
 		case "!!bool":
 			yv.value = model.NewBoolValue(value.Value == "true")
 		case "!!int":
-			i, err := strconv.Atoi(value.Value)
+			i, err := parseYAMLInt(value.Value)
 			if err != nil {
 				return err
 			}
-			yv.value = model.NewIntValue(int64(i))
+			yv.value = model.NewIntValue(i)
 		case "!!float":
 			f, err := strconv.ParseFloat(value.Value, 64)
 			if err != nil {
@@ -186,3 +187,25 @@ func (yv *yamlValue) UnmarshalYAML(value *yaml.Node) error {
 	}
 	return nil
 }
+
+func parseYAMLInt(s string) (int64, error) {
+	// Strip leading sign for prefix detection.
+	clean := s
+	if len(clean) > 0 && (clean[0] == '+' || clean[0] == '-') {
+		clean = clean[1:]
+	}
+
+	switch {
+	case strings.HasPrefix(clean, "0x") || strings.HasPrefix(clean, "0X"):
+		return strconv.ParseInt(s, 0, 64)
+	case strings.HasPrefix(clean, "0o") || strings.HasPrefix(clean, "0O"):
+		return strconv.ParseInt(s, 0, 64)
+	case strings.HasPrefix(clean, "0b") || strings.HasPrefix(clean, "0B"):
+		return strconv.ParseInt(s, 0, 64)
+	default:
+		// YAML 1.2 allows underscores in decimal integers (e.g. 1_000).
+		// strconv.ParseInt with base 10 does not support underscores,
+		// so we strip them before parsing.
+		return strconv.ParseInt(strings.ReplaceAll(s, "_", ""), 10, 64)
+	}
+}
diff --git a/parsing/yaml/yaml_test.go b/parsing/yaml/yaml_test.go
index 9093d4df..131ab8e9 100644
--- a/parsing/yaml/yaml_test.go
+++ b/parsing/yaml/yaml_test.go
@@ -204,6 +204,161 @@ name2: Tom
 `,
 	}.run)
 
+	t.Run("base numbers", func(t *testing.T) {
+		t.Run("standard", rwTestCase{
+			in: `10
+`,
+			out: `10
+`,
+		}.run)
+
+		t.Run("zero", rwTestCase{
+			in: `0
+`,
+			out: `0
+`,
+		}.run)
+
+		t.Run("negative", rwTestCase{
+			in: `-42
+`,
+			out: `-42
+`,
+		}.run)
+
+		t.Run("hex lowercase", rwTestCase{
+			in: `0x10
+`,
+			out: `16
+`,
+		}.run)
+
+		t.Run("hex uppercase letters", rwTestCase{
+			in: `0xff
+`,
+			out: `255
+`,
+		}.run)
+
+		t.Run("octal", rwTestCase{
+			in: `0o10
+`,
+			out: `8
+`,
+		}.run)
+
+		t.Run("binary", rwTestCase{
+			in: `0b10
+`,
+			out: `2
+`,
+		}.run)
+
+		t.Run("leading zero is decimal", rwTestCase{
+			in: `010
+`,
+			out: `10
+`,
+		}.run)
+
+		t.Run("hex in map", rwTestCase{
+			in: `val: 0x10
+`,
+			out: `val: 16
+`,
+		}.run)
+
+		t.Run("octal in map", rwTestCase{
+			in: `val: 0o77
+`,
+			out: `val: 63
+`,
+		}.run)
+
+		t.Run("mixed types in map", rwTestCase{
+			in: `dec: 42
+hex: 0xff
+oct: 0o77
+bin: 0b1010
+`,
+			out: `dec: 42
+hex: 255
+oct: 63
+bin: 10
+`,
+		}.run)
+
+		t.Run("positive sign", rwTestCase{
+			in: `+42
+`,
+			out: `42
+`,
+		}.run)
+
+		t.Run("positive hex", rwTestCase{
+			in: `+0x10
+`,
+			out: `16
+`,
+		}.run)
+
+		t.Run("positive octal", rwTestCase{
+			in: `+0o10
+`,
+			out: `8
+`,
+		}.run)
+
+		t.Run("positive binary", rwTestCase{
+			in: `+0b10
+`,
+			out: `2
+`,
+		}.run)
+
+		t.Run("negative hex", rwTestCase{
+			in: `-0x10
+`,
+			out: `-16
+`,
+		}.run)
+
+		t.Run("negative octal", rwTestCase{
+			in: `-0o10
+`,
+			out: `-8
+`,
+		}.run)
+
+		t.Run("negative binary", rwTestCase{
+			in: `-0b10
+`,
+			out: `-2
+`,
+		}.run)
+
+		t.Run("underscore decimal", rwTestCase{
+			in: `1_000
+`,
+			out: `1000
+`,
+		}.run)
+
+		t.Run("underscore hex", rwTestCase{
+			in: `0xFF_FF
+`,
+			out: `65535
+`,
+		}.run)
+
+		t.Run("underscore binary", rwTestCase{
+			in: `0b1010_1010
+`,
+			out: `170
+`,
+		}.run)
+	})
+
 	t.Run("bounded yaml expansion", func(t *testing.T) {
 		in := `a: &a ["lol","lol","lol","lol","lol","lol","lol","lol","lol"]
 b: &b [*a,*a,*a,*a,*a,*a,*a,*a,*a]
diff --git a/selector/parser/parser_test.go b/selector/parser/parser_test.go
index 0d875031..0851b725 100644
--- a/selector/parser/parser_test.go
+++ b/selector/parser/parser_test.go
@@ -61,6 +61,10 @@ func TestParser_Parse_HappyPath(t *testing.T) {
 			input:    "42",
 			expected: ast.NumberIntExpr{Value: 42},
 		}.run)
+		t.Run("leading zero decimal", happyTestCase{
+			input:    "010",
+			expected: ast.NumberIntExpr{Value: 10},
+		}.run)
 		t.Run("float", happyTestCase{
 			input:    "42.1",
 			expected: ast.NumberFloatExpr{Value: 42.1},