diff --git a/classes/range.js b/classes/range.js
index a791d912..d9e866de 100644
--- a/classes/range.js
+++ b/classes/range.js
@@ -81,8 +81,10 @@ class Range {
 
     // memoize range parsing for performance.
     // this is a very hot path, and fully deterministic.
-    const memoOpts = Object.keys(this.options).join(',')
-    const memoKey = `parseRange:${memoOpts}:${range}`
+    const memoOpts =
+      (this.options.includePrerelease && FLAG_INCLUDE_PRERELEASE) |
+      (this.options.loose && FLAG_LOOSE)
+    const memoKey = memoOpts + ':' + range
     const cached = cache.get(memoKey)
     if (cached) {
       return cached
@@ -190,6 +192,7 @@ class Range {
     return false
   }
 }
+
 module.exports = Range
 
 const LRU = require('lru-cache')
@@ -206,6 +209,7 @@ const {
   tildeTrimReplace,
   caretTrimReplace,
 } = require('../internal/re')
+const { FLAG_INCLUDE_PRERELEASE, FLAG_LOOSE } = require('../internal/constants')
 
 const isNullSet = c => c.value === '<0.0.0-0'
 const isAny = c => c.value === ''
diff --git a/internal/constants.js b/internal/constants.js
index cb2d76c2..25fab1ea 100644
--- a/internal/constants.js
+++ b/internal/constants.js
@@ -25,4 +25,6 @@ module.exports = {
   MAX_SAFE_INTEGER,
   RELEASE_TYPES,
   SEMVER_SPEC_VERSION,
+  FLAG_INCLUDE_PRERELEASE: 0b001,
+  FLAG_LOOSE: 0b010,
 }