diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4463397..3319046 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@ All notable changes to this project will be documented in this file. See [standa
 
 ## [Unreleased](https://github.com/motdotla/dotenv-expand/compare/v11.0.0...master)
 
-## [11.0.0](https://github.com/motdotla/dotenv-expand/compare/v10.0.0...v11.0.0) (2024-02-08)
+## [11.0.0](https://github.com/motdotla/dotenv-expand/compare/v10.0.0...v11.0.0) (2024-02-10)
 
 ### Added
 
@@ -15,6 +15,7 @@ All notable changes to this project will be documented in this file. See [standa
 ### Changed
 
 - Do not expand prior `process.env` environment variables. NOTE: make sure to see updated README regarding `dotenv.config({ processEnv: {} })` ([#104](https://github.com/motdotla/dotenv-expand/pull/104))
+- 🐞 handle `$var1$var2` ([#103](https://github.com/motdotla/dotenv-expand/issues/103), [#104](https://github.com/motdotla/dotenv-expand/pull/104))
 
 ### Removed
 
diff --git a/lib/main.js b/lib/main.js
index 567e7f3..6e42ca9 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -1,57 +1,93 @@
 'use strict'
 
-// like String.prototype.search but returns the last index
-function _searchLast (str, rgx) {
-  const matches = Array.from(str.matchAll(rgx))
-  return matches.length > 0 ? matches.slice(-1)[0].index : -1
-}
-
-function _interpolate (value, processEnv, parsed) {
-  // find the last unescaped dollar sign in the value to evaluate
-  const lastUnescapedDollarSignIndex = _searchLast(value, /(?!(?<=\\))\$/g)
-
-  // return early unless unescaped dollar sign
-  if (lastUnescapedDollarSignIndex === -1) {
-    return value
-  }
-
-  // This is the right-most group of variables in the string
-  const rightMostGroup = value.slice(lastUnescapedDollarSignIndex)
-
-  /**
-   * This finds the inner most variable/group divided
-   * by variable name and default value (if present)
-   * (
-   *   (?!(?<=\\))\$        // only match dollar signs that are not escaped
-   *   {?                   // optional opening curly brace
-   *     ([\w.]+)           // match the variable name
-   *     (?::-([^}\\]*))?   // match an optional default value
-   *   }?                   // optional closing curly brace
-   * )
-   */
-  const matchGroup = /((?!(?<=\\))\${?([\w.]+)(?::-([^}\\]*))?}?)/
-  const match = rightMostGroup.match(matchGroup)
-
-  if (match != null) {
-    const [, group, key, defaultValue] = match
-    const replacementString = processEnv[key] || defaultValue || parsed[key] || ''
-    const modifiedValue = value.replace(group, replacementString)
-
-    // return early for scenario like processEnv.PASSWORD = 'pas$word'
-    if (processEnv[key] && modifiedValue === processEnv[key]) {
-      return modifiedValue
-    }
-
-    return _interpolate(modifiedValue, processEnv, parsed)
-  }
-
-  return value
-}
+// // like String.prototype.search but returns the last index
+// function _searchLast (str, rgx) {
+//   const matches = Array.from(str.matchAll(rgx))
+//   return matches.length > 0 ? matches.slice(-1)[0].index : -1
+// }
+//
+// function _interpolate (value, processEnv, parsed) {
+//   // find the last unescaped dollar sign in the value to evaluate
+//   const lastUnescapedDollarSignIndex = _searchLast(value, /(?!(?<=\\))\$/g)
+//
+//   // return early unless unescaped dollar sign
+//   if (lastUnescapedDollarSignIndex === -1) {
+//     return value
+//   }
+//
+//   // This is the right-most group of variables in the string
+//   const rightMostGroup = value.slice(lastUnescapedDollarSignIndex)
+//
+//   console.log('rightMostGroup', rightMostGroup)
+//
+//   /**
+//    * This finds the inner most variable/group divided
+//    * by variable name and default value (if present)
+//    * (
+//    *   (?!(?<=\\))\$        // only match dollar signs that are not escaped
+//    *   {?                   // optional opening curly brace
+//    *     ([\w.]+)           // match the variable name
+//    *     (?::-([^}\\]*))?   // match an optional default value
+//    *   }?                   // optional closing curly brace
+//    * )
+//    */
+//   const matchGroup = /((?!(?<=\\))\${?([\w.]+)(?::-([^}\\]*))?}?)/
+//   const match = rightMostGroup.match(matchGroup)
+//
+//   if (match != null) {
+//     const [, group, key, defaultValue] = match
+//     const replacementString = processEnv[key] || defaultValue || parsed[key] || ''
+//     const modifiedValue = value.replace(group, replacementString)
+//
+//     // return early for scenario like processEnv.PASSWORD = 'pas$word'
+//     if (processEnv[key] && modifiedValue === processEnv[key]) {
+//       return modifiedValue
+//     }
+//
+//     return _interpolate(modifiedValue, processEnv, parsed)
+//   }
+//
+//   return value
+// }
 
 function _resolveEscapeSequences (value) {
   return value.replace(/\\\$/g, '$')
 }
 
+function interpolate (value, processEnv, parsed) {
+  // * /
+  // *   (\\)?            # is it escaped with a backslash?
+  // *   (\$)             # literal $
+  // *   (?!\()           # shouldnt be followed by parenthesis
+  // *   (\{?)            # first brace wrap opening
+  // *   ([\w.]+)         # key
+  // *   (?::-((?:\$\{(?:\$\{(?:\$\{[^}]*\}|[^}])*}|[^}])*}|[^}])+))? # optional default nested 3 times
+  // *   (\}?)            # last brace warp closing
+  // * /xi
+
+  const SUB_REGEX = /(\\)?(\$)(?!\()(\{?)([\w.]+)(?::-((?:\$\{(?:\$\{(?:\$\{[^}]*\}|[^}])*}|[^}])*}|[^}])+))?(\}?)/gi
+
+  return value.replace(SUB_REGEX, (match, escaped, dollarSign, openBrace, key, defaultValue, closeBrace) => {
+    if (escaped === '\\') {
+      return match.slice(1)
+    } else {
+      if (processEnv[key]) {
+        return processEnv[key]
+      }
+
+      if (defaultValue) {
+        if (defaultValue.startsWith('$')) {
+          return interpolate(defaultValue, processEnv, parsed)
+        } else {
+          return defaultValue
+        }
+      }
+
+      return parsed[key] || ''
+    }
+  })
+}
+
 function expand (options) {
   let processEnv = process.env
   if (options && options.processEnv != null) {
@@ -61,11 +97,11 @@ function expand (options) {
   for (const key in options.parsed) {
     let value = options.parsed[key]
 
-    // don't interpolate the processEnv value if it exists there already
+    // don't interpolate if it exists already in processEnv
     if (Object.prototype.hasOwnProperty.call(processEnv, key)) {
       value = processEnv[key]
     } else {
-      value = _interpolate(value, processEnv, options.parsed)
+      value = interpolate(value, processEnv, options.parsed)
     }
 
     options.parsed[key] = _resolveEscapeSequences(value)
diff --git a/tests/.env.test b/tests/.env.test
index f389b4a..32f236b 100644
--- a/tests/.env.test
+++ b/tests/.env.test
@@ -1,20 +1,23 @@
-NODE_ENV=test
 BASIC=basic
 BASIC_EXPAND=$BASIC
 MACHINE=machine_env
 MACHINE_EXPAND=$MACHINE
-UNDEFINED_EXPAND=$UNDEFINED_ENV_KEY
+
 ESCAPED_EXPAND=\$ESCAPED
-DEFINED_EXPAND_WITH_DEFAULT=${MACHINE:-default}
-DEFINED_EXPAND_WITH_DEFAULT_NESTED=${MACHINE:-${UNDEFINED_ENV_KEY:-default}}
-UNDEFINED_EXPAND_WITH_DEFINED_NESTED=${UNDEFINED_ENV_KEY:-${MACHINE:-default}}
-UNDEFINED_EXPAND_WITH_DEFAULT=${UNDEFINED_ENV_KEY:-default}
-UNDEFINED_EXPAND_WITH_DEFAULT_NESTED=${UNDEFINED_ENV_KEY:-${UNDEFINED_ENV_KEY_2:-default}}
-DEFINED_EXPAND_WITH_DEFAULT_NESTED_TWICE=${UNDEFINED_ENV_KEY:-${MACHINE}${UNDEFINED_ENV_KEY_3:-default}}
-UNDEFINED_EXPAND_WITH_DEFAULT_NESTED_TWICE=${UNDEFINED_ENV_KEY:-${UNDEFINED_ENV_KEY_2:-${UNDEFINED_ENV_KEY_3:-default}}}
-DEFINED_EXPAND_WITH_DEFAULT_WITH_SPECIAL_CHARACTERS=${MACHINE:-/default/path:with/colon}
-UNDEFINED_EXPAND_WITH_DEFAULT_WITH_SPECIAL_CHARACTERS=${UNDEFINED_ENV_KEY:-/default/path:with/colon}
-UNDEFINED_EXPAND_WITH_DEFAULT_WITH_SPECIAL_CHARACTERS_NESTED=${UNDEFINED_ENV_KEY:-${UNDEFINED_ENV_KEY_2:-/default/path:with/colon}}
+
+EXPAND_DEFAULT=${MACHINE:-default}
+EXPAND_DEFAULT_NESTED=${MACHINE:-${UNDEFINED:-default}}
+EXPAND_DEFAULT_NESTED_TWICE=${UNDEFINED:-${MACHINE}${UNDEFINED:-default}}
+EXPAND_DEFAULT_SPECIAL_CHARACTERS=${MACHINE:-/default/path:with/colon}
+
+UNDEFINED_EXPAND=$UNDEFINED
+UNDEFINED_EXPAND_NESTED=${UNDEFINED:-${MACHINE:-default}}
+UNDEFINED_EXPAND_DEFAULT=${UNDEFINED:-default}
+UNDEFINED_EXPAND_DEFAULT_NESTED=${UNDEFINED:-${UNDEFINED:-default}}
+UNDEFINED_EXPAND_DEFAULT_NESTED_TWICE=${UNDEFINED:-${UNDEFINED:-${UNDEFINED:-default}}}
+UNDEFINED_EXPAND_DEFAULT_SPECIAL_CHARACTERS=${UNDEFINED:-/default/path:with/colon}
+UNDEFINED_EXPAND_DEFAULT_SPECIAL_CHARACTERS_NESTED=${UNDEFINED:-${UNDEFINED_2:-/default/path:with/colon}}
+
 MONGOLAB_DATABASE=heroku_db
 MONGOLAB_USER=username
 MONGOLAB_PASSWORD=password
@@ -25,12 +28,19 @@ MONGOLAB_URI=mongodb://${MONGOLAB_USER}:${MONGOLAB_PASSWORD}@${MONGOLAB_DOMAIN}:
 MONGOLAB_USER_RECURSIVELY=${MONGOLAB_USER}:${MONGOLAB_PASSWORD}
 MONGOLAB_URI_RECURSIVELY=mongodb://${MONGOLAB_USER_RECURSIVELY}@${MONGOLAB_DOMAIN}:${MONGOLAB_PORT}/${MONGOLAB_DATABASE}
 
-WITHOUT_CURLY_BRACES_URI=mongodb://$MONGOLAB_USER:$MONGOLAB_PASSWORD@$MONGOLAB_DOMAIN:$MONGOLAB_PORT/$MONGOLAB_DATABASE
-WITHOUT_CURLY_BRACES_USER_RECURSIVELY=$MONGOLAB_USER:$MONGOLAB_PASSWORD
-WITHOUT_CURLY_BRACES_URI_RECURSIVELY=mongodb://$MONGOLAB_USER_RECURSIVELY@$MONGOLAB_DOMAIN:$MONGOLAB_PORT/$MONGOLAB_DATABASE
-WITHOUT_CURLY_BRACES_UNDEFINED_EXPAND_WITH_DEFAULT_WITH_SPECIAL_CHARACTERS=$UNDEFINED_ENV_KEY:-/default/path:with/colon
+NO_CURLY_BRACES_URI=mongodb://$MONGOLAB_USER:$MONGOLAB_PASSWORD@$MONGOLAB_DOMAIN:$MONGOLAB_PORT/$MONGOLAB_DATABASE
+NO_CURLY_BRACES_USER_RECURSIVELY=$MONGOLAB_USER:$MONGOLAB_PASSWORD
+NO_CURLY_BRACES_URI_RECURSIVELY=mongodb://$MONGOLAB_USER_RECURSIVELY@$MONGOLAB_DOMAIN:$MONGOLAB_PORT/$MONGOLAB_DATABASE
+NO_CURLY_BRACES_UNDEFINED_EXPAND_DEFAULT_SPECIAL_CHARACTERS=$UNDEFINED:-/default/path:with/colon
 
 POSTGRESQL.BASE.USER=postgres
 POSTGRESQL.MAIN.USER=${POSTGRESQL.BASE.USER}
 
 DOLLAR=$
+
+ONE=one
+TWO=two
+ONETWO=${ONE}${TWO}
+ONETWO_SIMPLE=${ONE}$TWO
+ONETWO_SIMPLE2=$ONE${TWO}
+ONETWO_SUPER_SIMPLE=$ONE$TWO
diff --git a/tests/main.js b/tests/main.js
index 210f0fe..3cf06bb 100644
--- a/tests/main.js
+++ b/tests/main.js
@@ -67,7 +67,7 @@ t.test('does not expand environment variables existing already on the machine th
 t.test('expands missing environment variables to an empty string', ct => {
   const dotenv = {
     parsed: {
-      UNDEFINED_EXPAND: '$UNDEFINED_ENV_KEY'
+      UNDEFINED_EXPAND: '$UNDEFINED'
     }
   }
   const parsed = dotenvExpand.expand(dotenv).parsed
@@ -194,7 +194,7 @@ t.test('expands environment variables existing already on the machine even with
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   dotenvExpand.expand(dotenv)
 
-  ct.equal(process.env.DEFINED_EXPAND_WITH_DEFAULT, 'machine')
+  ct.equal(process.env.EXPAND_DEFAULT, 'machine')
 
   ct.end()
 })
@@ -205,7 +205,7 @@ t.test('expands environment variables existing already on the machine even with
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   dotenvExpand.expand(dotenv)
 
-  ct.equal(process.env.DEFINED_EXPAND_WITH_DEFAULT_NESTED, 'machine')
+  ct.equal(process.env.EXPAND_DEFAULT_NESTED, 'machine')
 
   ct.end()
 })
@@ -216,7 +216,7 @@ t.test('expands environment variables undefined with one already on the machine
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   dotenvExpand.expand(dotenv)
 
-  ct.equal(process.env.UNDEFINED_EXPAND_WITH_DEFINED_NESTED, 'machine')
+  ct.equal(process.env.UNDEFINED_EXPAND_NESTED, 'machine')
 
   ct.end()
 })
@@ -225,7 +225,7 @@ t.test('expands missing environment variables to an empty string but replaces wi
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   const parsed = dotenvExpand.expand(dotenv).parsed
 
-  ct.equal(parsed.UNDEFINED_EXPAND_WITH_DEFAULT, 'default')
+  ct.equal(parsed.UNDEFINED_EXPAND_DEFAULT, 'default')
 
   ct.end()
 })
@@ -234,7 +234,7 @@ t.test('expands environent variables and concats with default nested', ct => {
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   const parsed = dotenvExpand.expand(dotenv).parsed
 
-  ct.equal(parsed.DEFINED_EXPAND_WITH_DEFAULT_NESTED_TWICE, 'machinedefault')
+  ct.equal(parsed.EXPAND_DEFAULT_NESTED_TWICE, 'machinedefault')
 
   ct.end()
 })
@@ -243,7 +243,7 @@ t.test('expands missing environment variables to an empty string but replaces wi
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   const parsed = dotenvExpand.expand(dotenv).parsed
 
-  ct.equal(parsed.UNDEFINED_EXPAND_WITH_DEFAULT_NESTED, 'default')
+  ct.equal(parsed.UNDEFINED_EXPAND_DEFAULT_NESTED, 'default')
 
   ct.end()
 })
@@ -252,7 +252,7 @@ t.test('expands missing environment variables to an empty string but replaces wi
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   const parsed = dotenvExpand.expand(dotenv).parsed
 
-  ct.equal(parsed.UNDEFINED_EXPAND_WITH_DEFAULT_NESTED_TWICE, 'default')
+  ct.equal(parsed.UNDEFINED_EXPAND_DEFAULT_NESTED_TWICE, 'default')
 
   ct.end()
 })
@@ -290,7 +290,7 @@ t.test('multiple expand', ct => {
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   const parsed = dotenvExpand.expand(dotenv).parsed
 
-  ct.equal(parsed.WITHOUT_CURLY_BRACES_URI, 'mongodb://username:password@abcd1234.mongolab.com:12345/heroku_db')
+  ct.equal(parsed.NO_CURLY_BRACES_URI, 'mongodb://username:password@abcd1234.mongolab.com:12345/heroku_db')
 
   ct.end()
 })
@@ -299,7 +299,7 @@ t.test('should expand recursively', ct => {
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   const parsed = dotenvExpand.expand(dotenv).parsed
 
-  ct.equal(parsed.WITHOUT_CURLY_BRACES_URI_RECURSIVELY, 'mongodb://username:password@abcd1234.mongolab.com:12345/heroku_db')
+  ct.equal(parsed.NO_CURLY_BRACES_URI_RECURSIVELY, 'mongodb://username:password@abcd1234.mongolab.com:12345/heroku_db')
 
   ct.end()
 })
@@ -326,7 +326,7 @@ t.test('expands environment variables existing already on the machine even with
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   const parsed = dotenvExpand.expand(dotenv).parsed
 
-  ct.equal(parsed.DEFINED_EXPAND_WITH_DEFAULT_WITH_SPECIAL_CHARACTERS, 'machine')
+  ct.equal(parsed.EXPAND_DEFAULT_SPECIAL_CHARACTERS, 'machine')
 
   ct.end()
 })
@@ -335,8 +335,8 @@ t.test('should expand with default value correctly', ct => {
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   const parsed = dotenvExpand.expand(dotenv).parsed
 
-  ct.equal(parsed.UNDEFINED_EXPAND_WITH_DEFAULT_WITH_SPECIAL_CHARACTERS, '/default/path:with/colon')
-  ct.equal(parsed.WITHOUT_CURLY_BRACES_UNDEFINED_EXPAND_WITH_DEFAULT_WITH_SPECIAL_CHARACTERS, '/default/path:with/colon')
+  ct.equal(parsed.UNDEFINED_EXPAND_DEFAULT_SPECIAL_CHARACTERS, '/default/path:with/colon')
+  ct.equal(parsed.NO_CURLY_BRACES_UNDEFINED_EXPAND_DEFAULT_SPECIAL_CHARACTERS, '/default/path:with/colon')
 
   ct.end()
 })
@@ -345,7 +345,7 @@ t.test('should expand with default nested value correctly', ct => {
   const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
   const parsed = dotenvExpand.expand(dotenv).parsed
 
-  ct.equal(parsed.UNDEFINED_EXPAND_WITH_DEFAULT_WITH_SPECIAL_CHARACTERS_NESTED, '/default/path:with/colon')
+  ct.equal(parsed.UNDEFINED_EXPAND_DEFAULT_SPECIAL_CHARACTERS_NESTED, '/default/path:with/colon')
 
   ct.end()
 })
@@ -367,3 +367,15 @@ t.test('handles value of only $', ct => {
 
   ct.end()
 })
+
+t.test('handles $one$two', ct => {
+  const dotenv = require('dotenv').config({ path: 'tests/.env.test', processEnv: {} })
+  const parsed = dotenvExpand.expand(dotenv).parsed
+
+  ct.equal(parsed.ONETWO, 'onetwo')
+  ct.equal(parsed.ONETWO_SIMPLE, 'onetwo')
+  ct.equal(parsed.ONETWO_SIMPLE2, 'onetwo')
+  ct.equal(parsed.ONETWO_SUPER_SIMPLE, 'onetwo')
+
+  ct.end()
+})