diff --git a/README.md b/README.md
index 1f160289..ecbf3984 100644
--- a/README.md
+++ b/README.md
@@ -37,7 +37,7 @@ The following features, which are not supported in standard JSON, have been adde
 - Object keys may be unquoted ECMAScript 5.1 _[IdentifierName]_ s.
 - Unquoted object keys may include character escapes.
 - Character escapes with two hex digits (`\xXX`) are supported for parsing, as well as the standard four digit `\uXXXX` form.
-- Object keys may be single quoted or backtick quoted.
+- Object keys may be single quoted or backtick quoted (using backticks does not, however, invoke string interpolation).
 - Object key/value pairs may have a single trailing comma.
 
 ### Arrays
diff --git a/lib/bignumber-util.js b/lib/bignumber-util.js
index a37d30f2..752bbdf3 100644
--- a/lib/bignumber-util.js
+++ b/lib/bignumber-util.js
@@ -86,15 +86,15 @@ module.exports = {
     }
 
     // Try to recover sign of negative zero.
-    if (Object.is(value, -0) || /-0\b/.test(value.valueOf().toString())) {
+    if (!str.startsWith('-') && (Object.is(value, -0) || /-0\b/.test(value.valueOf().toString()))) {
       str = '-' + str;
     }
 
     const special = /[-+]?Infinity|NaN/.test(str);
 
     if (goBig) {
-      if (special) {
-        return str;
+      if (special && suffix && !noSuffix) {
+        str += '_';
       }
 
       return str + (noSuffix ? '' : suffix);
diff --git a/lib/parse.js b/lib/parse.js
index 490262df..8dd0eae6 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -151,6 +151,8 @@ module.exports = function parse(text, reviver, newOptions) {
     },
 
     value() {
+      let trailingUnderscore = false;
+
       switch (c) {
         case '{':
         case '[':
@@ -218,11 +220,41 @@ module.exports = function parse(text, reviver, newOptions) {
         case 'I':
           read();
           literal('nfinity');
+
+          if (peek() === '_') {
+            read();
+            trailingUnderscore = true;
+          }
+
+          if (peek() === 'm') {
+            read();
+            return newToken(big.getBigDecimalType(), big.toBigDecimal(Infinity));
+          }
+
+          if (trailingUnderscore) {
+            throw invalidChar('_');
+          }
+
           return newToken('numeric', Infinity);
 
         case 'N':
           read();
           literal('aN');
+
+          if (peek() === '_') {
+            read();
+            trailingUnderscore = true;
+          }
+
+          if (peek() === 'm') {
+            read();
+            return newToken(big.getBigDecimalType(), big.toBigDecimal(NaN));
+          }
+
+          if (trailingUnderscore) {
+            throw invalidChar('_');
+          }
+
           return newToken('numeric', NaN);
 
         case "'":
@@ -309,6 +341,8 @@ module.exports = function parse(text, reviver, newOptions) {
     },
 
     sign() {
+      let trailingUnderscore = false;
+
       switch (c) {
         case '.':
           buffer = read();
@@ -341,11 +375,41 @@ module.exports = function parse(text, reviver, newOptions) {
         case 'I':
           read();
           literal('nfinity');
+
+          if (peek() === '_') {
+            read();
+            trailingUnderscore = true;
+          }
+
+          if (peek() === 'm') {
+            read();
+            return newToken(big.getBigDecimalType(), big.toBigDecimal(sign * Infinity));
+          }
+
+          if (trailingUnderscore) {
+            throw invalidChar('_');
+          }
+
           return newToken('numeric', sign * Infinity);
 
         case 'N':
           read();
           literal('aN');
+
+          if (peek() === '_') {
+            read();
+            trailingUnderscore = true;
+          }
+
+          if (peek() === 'm') {
+            read();
+            return newToken(big.getBigDecimalType(), big.toBigDecimal(NaN));
+          }
+
+          if (trailingUnderscore) {
+            throw invalidChar('_');
+          }
+
           return newToken('numeric', NaN);
       }
 
diff --git a/package.json b/package.json
index 87976b41..a98849f9 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "json-z",
-  "version": "3.0.4",
+  "version": "3.0.5",
   "description": "JSON for everyone.",
   "main": "lib/index.js",
   "types": "lib/index.d.ts",
@@ -23,7 +23,7 @@
     "preversion": "npm run production",
     "production": "npm run lint && npm test && npm run build",
     "test": "tap -Rspec --100 test",
-    "quick-test": "tap -T -Rspec test/stringify.spec.js",
+    "quick-test": "tap -T -Rspec test/parse.spec.js",
     "version": "npm run build-package && git add package.json5"
   },
   "repository": {
diff --git a/test/errors.spec.js b/test/errors.spec.js
index da7f61cb..96911a02 100644
--- a/test/errors.spec.js
+++ b/test/errors.spec.js
@@ -216,6 +216,7 @@ describe('JSONZ', () => {
           '0x_12', '0x1__2', '0x12_',
           '0o_12', '0o1__2', '0o12_',
           '0b_11', '0b1__1', '0b11_',
+          'NaN_', '-NaN_', 'Infinity_', '-Infinity_',
         ];
 
         for (const badNumber of badNumbers) {
diff --git a/test/parse.spec.js b/test/parse.spec.js
index 7d68f28c..336c38fa 100644
--- a/test/parse.spec.js
+++ b/test/parse.spec.js
@@ -19,6 +19,9 @@ function equalBigNumber(a, b) {
   else if (!!a !== !!b || !a) {
     return false;
   }
+  else if (typeof a.isNaN === 'function' && a.isNaN()) {
+    return typeof b.isNaN === 'function' && b.isNaN();
+  }
   else if (typeof a.equals === 'function') {
     return a.equals(b);
   }
@@ -327,6 +330,14 @@ t.test('parse(text)', t => {
       );
     }
 
+    t.ok(equalBigNumber(JSONZ.parse('NaNm'), Decimal(NaN)), 'parses NaNm');
+    t.ok(equalBigNumber(JSONZ.parse('NaN_m'), Decimal(NaN)), 'parses NaN_m');
+    t.ok(equalBigNumber(JSONZ.parse('+NaN_m'), Decimal(NaN)), 'parses +NaN_m');
+    t.ok(equalBigNumber(JSONZ.parse('Infinitym'), Decimal(Infinity)), 'parses Infinitym');
+    t.ok(equalBigNumber(JSONZ.parse('Infinity_m'), Decimal(Infinity)), 'parses Infinity_m');
+    t.ok(equalBigNumber(JSONZ.parse('-Infinitym'), Decimal(-Infinity)), 'parses -Infinitym');
+    t.ok(equalBigNumber(JSONZ.parse('-Infinity_m'), Decimal(-Infinity)), 'parses -Infinity_m');
+
     JSONZ.setBigDecimal(null);
     t.ok(big.getBigDecimalType() === 'numeric', 'can disable big decimal support');
     JSONZ.setBigDecimal(Decimal);
diff --git a/test/stringify.spec.js b/test/stringify.spec.js
index e80fdf2f..a5f96d51 100644
--- a/test/stringify.spec.js
+++ b/test/stringify.spec.js
@@ -162,6 +162,10 @@ describe('JSONZ', () => {
         assert.strictEqual(JSONZ.stringify(-0), '-0');
       });
 
+      it('doesn\'t create double negative sign', () => {
+        assert.strictEqual(JSONZ.stringify(-0.1), '-0.1');
+      });
+
       it('stringifies non-finite numbers', () => {
         assert.strictEqual(JSONZ.stringify([Infinity, -Infinity, NaN]), '[Infinity,-Infinity,NaN]');
       });
@@ -212,7 +216,7 @@ describe('JSONZ', () => {
 
         it('stringifies bigdecimal special values', () => {
           assert.strictEqual(JSONZ.stringify([big.toBigDecimal(1 / 0), big.toBigDecimal(-1 / 0), big.toBigDecimal(0 / 0)]),
-            '[Infinity,-Infinity,NaN]');
+            '[Infinity_m,-Infinity_m,NaN_m]');
 
           assert.strictEqual(JSONZ.stringify(
             big.toBigDecimal(1 / 0),