diff --git a/src/lexer/numbers.js b/src/lexer/numbers.js
index 484b35a99..edb5e4022 100644
--- a/src/lexer/numbers.js
+++ b/src/lexer/numbers.js
@@ -23,7 +23,7 @@ module.exports = {
       if (ch === "x" || ch === "X") {
         ch = this.input();
         if (ch !== "_" && this.is_HEX()) {
-          return this.consume_HNUM();
+          return this.consume_hexadecimal();
         } else {
           this.unput(ch ? 2 : 1);
         }
@@ -31,14 +31,14 @@ module.exports = {
       } else if (ch === "b" || ch === "B") {
         ch = this.input();
         if ((ch !== "_" && ch === "0") || ch === "1") {
-          return this.consume_BNUM();
+          return this.consume_binary();
         } else {
           this.unput(ch ? 2 : 1);
         }
       } else if (ch === "o" || ch === "O") {
         ch = this.input();
         if (ch !== "_" && this.is_OCTAL()) {
-          return this.consume_ONUM();
+          return this.consume_octal();
         } else {
           this.unput(ch ? 2 : 1);
         }
@@ -94,7 +94,7 @@ module.exports = {
           ch = this.input();
         }
         if (this.is_NUM_START()) {
-          this.consume_LNUM();
+          this.consume_decimal_digits();
           return this.tok.T_DNUMBER;
         }
         this.unput(ch ? undo : undo - 1); // keep only 1
@@ -123,49 +123,44 @@ module.exports = {
       return this.tok.T_DNUMBER;
     }
   },
-  // read hexa
-  consume_HNUM() {
+  consume_prefixed_digits(isValid) {
+    let prev = this._input[this.offset - 1];
     while (this.offset < this.size) {
       const ch = this.input();
-      if (!this.is_HEX()) {
+      if (!isValid.call(this)) {
         if (ch) this.unput(1);
         break;
       }
-    }
-    return this.tok.T_LNUMBER;
-  },
-  // read a generic number
-  consume_LNUM() {
-    while (this.offset < this.size) {
-      const ch = this.input();
-      if (!this.is_NUM()) {
-        if (ch) this.unput(1);
+      if (ch === "_" && prev === "_") {
+        this.unput(2);
+        prev = null;
         break;
       }
+      prev = ch;
     }
+    if (prev === "_") this.unput(1);
     return this.tok.T_LNUMBER;
   },
-  // read binary
-  consume_BNUM() {
-    let ch;
-    while (this.offset < this.size) {
-      ch = this.input();
-      if (ch !== "0" && ch !== "1" && ch !== "_") {
-        if (ch) this.unput(1);
-        break;
-      }
-    }
-    return this.tok.T_LNUMBER;
+  consume_hexadecimal() {
+    return this.consume_prefixed_digits(this.is_HEX);
   },
-  // read an octal number
-  consume_ONUM() {
+  consume_decimal_digits() {
     while (this.offset < this.size) {
       const ch = this.input();
-      if (!this.is_OCTAL()) {
+      if (!this.is_NUM()) {
         if (ch) this.unput(1);
         break;
       }
     }
     return this.tok.T_LNUMBER;
   },
+  consume_binary() {
+    return this.consume_prefixed_digits(function () {
+      const ch = this._input[this.offset - 1];
+      return ch === "0" || ch === "1" || ch === "_";
+    });
+  },
+  consume_octal() {
+    return this.consume_prefixed_digits(this.is_OCTAL);
+  },
 };
diff --git a/test/snapshot/__snapshots__/number.test.js.snap b/test/snapshot/__snapshots__/number.test.js.snap
index a9bfd38de..d7a2f1a77 100644
--- a/test/snapshot/__snapshots__/number.test.js.snap
+++ b/test/snapshot/__snapshots__/number.test.js.snap
@@ -1,5 +1,98 @@
 // Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
 
+exports[`Test numbers binary consecutive underscores 1`] = `
+Program {
+  "children": [
+    ExpressionStatement {
+      "expression": Assign {
+        "kind": "assign",
+        "left": Variable {
+          "curly": false,
+          "kind": "variable",
+          "name": "e",
+        },
+        "operator": "=",
+        "right": Number {
+          "kind": "number",
+          "value": "0b1",
+        },
+      },
+      "kind": "expressionstatement",
+    },
+    ExpressionStatement {
+      "expression": undefined,
+      "kind": "expressionstatement",
+    },
+  ],
+  "errors": [
+    Error {
+      "expected": ";",
+      "kind": "error",
+      "line": 1,
+      "message": "Parse Error : syntax error, unexpected '__0' (T_STRING), expecting ';' on line 1",
+      "token": "'__0' (T_STRING)",
+    },
+    Error {
+      "expected": "EXPR",
+      "kind": "error",
+      "line": 1,
+      "message": "Parse Error : syntax error on line 1",
+      "token": "the end of file (EOF)",
+    },
+  ],
+  "kind": "program",
+}
+`;
+
+exports[`Test numbers binary trailing underscore 1`] = `
+Program {
+  "children": [
+    ExpressionStatement {
+      "expression": Assign {
+        "kind": "assign",
+        "left": Variable {
+          "curly": false,
+          "kind": "variable",
+          "name": "e",
+        },
+        "operator": "=",
+        "right": Number {
+          "kind": "number",
+          "value": "0b1",
+        },
+      },
+      "kind": "expressionstatement",
+    },
+    ExpressionStatement {
+      "expression": Bin {
+        "kind": "bin",
+        "left": Name {
+          "kind": "name",
+          "name": "_",
+          "resolution": "uqn",
+        },
+        "right": Number {
+          "kind": "number",
+          "value": "1",
+        },
+        "type": "+",
+      },
+      "kind": "expressionstatement",
+    },
+  ],
+  "errors": [
+    Error {
+      "expected": ";",
+      "kind": "error",
+      "line": 1,
+      "message": "Parse Error : syntax error, unexpected '_' (T_STRING), expecting ';' on line 1",
+      "token": "'_' (T_STRING)",
+    },
+  ],
+  "kind": "program",
+}
+`;
+
 exports[`Test numbers binary with 2 1`] = `
 Program {
   "children": [
@@ -138,6 +231,99 @@ Program {
 }
 `;
 
+exports[`Test numbers hex consecutive underscores 1`] = `
+Program {
+  "children": [
+    ExpressionStatement {
+      "expression": Assign {
+        "kind": "assign",
+        "left": Variable {
+          "curly": false,
+          "kind": "variable",
+          "name": "e",
+        },
+        "operator": "=",
+        "right": Number {
+          "kind": "number",
+          "value": "0x1",
+        },
+      },
+      "kind": "expressionstatement",
+    },
+    ExpressionStatement {
+      "expression": undefined,
+      "kind": "expressionstatement",
+    },
+  ],
+  "errors": [
+    Error {
+      "expected": ";",
+      "kind": "error",
+      "line": 1,
+      "message": "Parse Error : syntax error, unexpected '__2' (T_STRING), expecting ';' on line 1",
+      "token": "'__2' (T_STRING)",
+    },
+    Error {
+      "expected": "EXPR",
+      "kind": "error",
+      "line": 1,
+      "message": "Parse Error : syntax error on line 1",
+      "token": "the end of file (EOF)",
+    },
+  ],
+  "kind": "program",
+}
+`;
+
+exports[`Test numbers hex trailing underscore 1`] = `
+Program {
+  "children": [
+    ExpressionStatement {
+      "expression": Assign {
+        "kind": "assign",
+        "left": Variable {
+          "curly": false,
+          "kind": "variable",
+          "name": "e",
+        },
+        "operator": "=",
+        "right": Number {
+          "kind": "number",
+          "value": "0x1",
+        },
+      },
+      "kind": "expressionstatement",
+    },
+    ExpressionStatement {
+      "expression": Bin {
+        "kind": "bin",
+        "left": Name {
+          "kind": "name",
+          "name": "_",
+          "resolution": "uqn",
+        },
+        "right": Number {
+          "kind": "number",
+          "value": "1",
+        },
+        "type": "+",
+      },
+      "kind": "expressionstatement",
+    },
+  ],
+  "errors": [
+    Error {
+      "expected": ";",
+      "kind": "error",
+      "line": 1,
+      "message": "Parse Error : syntax error, unexpected '_' (T_STRING), expecting ';' on line 1",
+      "token": "'_' (T_STRING)",
+    },
+  ],
+  "kind": "program",
+}
+`;
+
 exports[`Test numbers hexa without hex 1`] = `
 Program {
   "children": [
@@ -222,6 +408,99 @@ Program {
 }
 `;
 
+exports[`Test numbers octal consecutive underscores 1`] = `
+Program {
+  "children": [
+    ExpressionStatement {
+      "expression": Assign {
+        "kind": "assign",
+        "left": Variable {
+          "curly": false,
+          "kind": "variable",
+          "name": "e",
+        },
+        "operator": "=",
+        "right": Number {
+          "kind": "number",
+          "value": "0o7",
+        },
+      },
+      "kind": "expressionstatement",
+    },
+    ExpressionStatement {
+      "expression": undefined,
+      "kind": "expressionstatement",
+    },
+  ],
+  "errors": [
+    Error {
+      "expected": ";",
+      "kind": "error",
+      "line": 1,
+      "message": "Parse Error : syntax error, unexpected '__1' (T_STRING), expecting ';' on line 1",
+      "token": "'__1' (T_STRING)",
+    },
+    Error {
+      "expected": "EXPR",
+      "kind": "error",
+      "line": 1,
+      "message": "Parse Error : syntax error on line 1",
+      "token": "the end of file (EOF)",
+    },
+  ],
+  "kind": "program",
+}
+`;
+
+exports[`Test numbers octal trailing underscore 1`] = `
+Program {
+  "children": [
+    ExpressionStatement {
+      "expression": Assign {
+        "kind": "assign",
+        "left": Variable {
+          "curly": false,
+          "kind": "variable",
+          "name": "e",
+        },
+        "operator": "=",
+        "right": Number {
+          "kind": "number",
+          "value": "0o7",
+        },
+      },
+      "kind": "expressionstatement",
+    },
+    ExpressionStatement {
+      "expression": Bin {
+        "kind": "bin",
+        "left": Name {
+          "kind": "name",
+          "name": "_",
+          "resolution": "uqn",
+        },
+        "right": Number {
+          "kind": "number",
+          "value": "1",
+        },
+        "type": "+",
+      },
+      "kind": "expressionstatement",
+    },
+  ],
+  "errors": [
+    Error {
+      "expected": ";",
+      "kind": "error",
+      "line": 1,
+      "message": "Parse Error : syntax error, unexpected '_' (T_STRING), expecting ';' on line 1",
+      "token": "'_' (T_STRING)",
+    },
+  ],
+  "kind": "program",
+}
+`;
+
 exports[`Test numbers test common cases 1`] = `
 Program {
   "children": [
@@ -402,6 +681,63 @@ Program {
 }
 `;
 
+exports[`Test numbers test underscore separators in hex/binary/octal 1`] = `
+Program {
+  "children": [
+    ExpressionStatement {
+      "expression": Assign {
+        "kind": "assign",
+        "left": Variable {
+          "curly": false,
+          "kind": "variable",
+          "name": "a",
+        },
+        "operator": "=",
+        "right": Number {
+          "kind": "number",
+          "value": "0x1_A2_B3",
+        },
+      },
+      "kind": "expressionstatement",
+    },
+    ExpressionStatement {
+      "expression": Assign {
+        "kind": "assign",
+        "left": Variable {
+          "curly": false,
+          "kind": "variable",
+          "name": "b",
+        },
+        "operator": "=",
+        "right": Number {
+          "kind": "number",
+          "value": "0b1010_0101",
+        },
+      },
+      "kind": "expressionstatement",
+    },
+    ExpressionStatement {
+      "expression": Assign {
+        "kind": "assign",
+        "left": Variable {
+          "curly": false,
+          "kind": "variable",
+          "name": "c",
+        },
+        "operator": "=",
+        "right": Number {
+          "kind": "number",
+          "value": "0o7_6_5",
+        },
+      },
+      "kind": "expressionstatement",
+    },
+  ],
+  "errors": [],
+  "kind": "program",
+}
+`;
+
 exports[`Test numbers underscore #1 1`] = `
 Program {
   "children": [
diff --git a/test/snapshot/number.test.js b/test/snapshot/number.test.js
index 84b6960b0..c018e76fd 100644
--- a/test/snapshot/number.test.js
+++ b/test/snapshot/number.test.js
@@ -19,6 +19,16 @@ describe("Test numbers", function () {
     ).toMatchSnapshot();
   });
 
+  it("test underscore separators in hex/binary/octal", function () {
+    expect(
+      parser.parseEval(`
+      $a = 0x1_A2_B3;
+      $b = 0b1010_0101;
+      $c = 0o7_6_5;
+    `),
+    ).toMatchSnapshot();
+  });
+
   it.each([
     ["hexa without hex", "$a = 0xx;"],
     ["binary with 2", "$b = 0b2;"],
@@ -33,6 +43,12 @@ describe("Test numbers", function () {
     ["underscore #3", "$e = 7_.0;"],
     ["underscore #4", "$e = 7e_0;"],
     ["underscore #5", "$e = 7_e0;"],
+    ["hex consecutive underscores", "$e = 0x1__2;"],
+    ["hex trailing underscore", "$e = 0x1_ + 1;"],
+    ["binary consecutive underscores", "$e = 0b1__0;"],
+    ["binary trailing underscore", "$e = 0b1_ + 1;"],
+    ["octal consecutive underscores", "$e = 0o7__1;"],
+    ["octal trailing underscore", "$e = 0o7_ + 1;"],
   ])("%s", function (_, code) {
     const ast = parser.parseEval(code, {
       parser: {