diff --git a/common/web/types/src/ldml-keyboard/unicodeset-parser-api.ts b/common/web/types/src/ldml-keyboard/unicodeset-parser-api.ts
index 6e6cb9445c..0c890aa95a 100644
--- a/common/web/types/src/ldml-keyboard/unicodeset-parser-api.ts
+++ b/common/web/types/src/ldml-keyboard/unicodeset-parser-api.ts
@@ -6,9 +6,9 @@ export interface UnicodeSetParser {
   /**
    * Parse a UnicodeSet into ranges
    * @param pattern string to parse such as `[a-z]`
-   * @param bufferSize number of ranges to allow for
+   * @param rangeCount number of ranges to allow for
    */
-  parseUnicodeSet(pattern: string, bufferSize: number) : UnicodeSet | null;
+  parseUnicodeSet(pattern: string, rangeCount: number) : UnicodeSet | null;
   /**
    * Calculate the number of ranges in a UnicodeSet
    * @param pattern string to parse such as `[a-z]`
@@ -18,9 +18,16 @@ export interface UnicodeSetParser {
 }
 
 /**
- * Represents a parsed UnicodeSet
+ * Parsed UnicodeSet, return value of of parseUnicodeSet()
  */
 export class UnicodeSet {
+  /**
+   * A UnicodeSet in range form.
+   * For example, `[ħa-z]` will parse to
+   * ranges = `[[0x41, 0x7A], [0x0127, 0x0127]]` meaning `[a,z], [ħ,ħ]`
+   * @param pattern the pattern per UnicodeSet syntax such as `[a-z]`
+   * @param ranges array of 2-element arrays, 'start' and 'end'.
+   */
   constructor(public pattern: string, public ranges: number[][]) {
   }
   /**
diff --git a/developer/src/kmc-kmn/src/compiler/compiler.ts b/developer/src/kmc-kmn/src/compiler/compiler.ts
index dc35a3a697..499c74abe9 100644
--- a/developer/src/kmc-kmn/src/compiler/compiler.ts
+++ b/developer/src/kmc-kmn/src/compiler/compiler.ts
@@ -228,22 +228,19 @@ export class KmnCompiler implements UnicodeSetParser {
   /**
    *
    * @param pattern UnicodeSet pattern such as `[a-z]`
-   * @param bufferSize guess as to the buffer size
+   * @param rangeCount number of ranges to allocate
    * @returns UnicodeSet accessor object, or null on failure
    */
-  public parseUnicodeSet(pattern: string, bufferSize: number) : UnicodeSet | null {
+  public parseUnicodeSet(pattern: string, rangeCount: number) : UnicodeSet | null {
     if(!this.verifyInitialized()) {
       /* c8 ignore next 2 */
       return null;
     }
 
-    if (!bufferSize) {
-      /* c8 ignore next 2 */
-      bufferSize = 100; // TODO-LDML: Preflight mode? Reuse buffer?
-    }
-    const buf = this.Module.asm.malloc(bufferSize * 2 * this.Module.HEAPU32.BYTES_PER_ELEMENT);
+    const buf = this.Module.asm.malloc(rangeCount * 2 * this.Module.HEAPU32.BYTES_PER_ELEMENT);
     // TODO-LDML: Catch OOM
-    const rc = this.Module.kmcmp_parseUnicodeSet(pattern, buf, bufferSize);
+    /** return code, if positive: range count */
+    const rc = this.Module.kmcmp_parseUnicodeSet(pattern, buf, rangeCount * 2);
     if (rc >= 0) {
       const ranges = [];
       const startu = (buf / this.Module.HEAPU32.BYTES_PER_ELEMENT);