diff --git a/scripts/build-declarations.js b/scripts/build-declarations.js
index 37b840e..a9846fe 100755
--- a/scripts/build-declarations.js
+++ b/scripts/build-declarations.js
@@ -69,7 +69,7 @@ function extractFunctions(contents, isTool) {
             funcName = match[1];
           }
         }
-        if (funcName) {
+        if (funcName && !funcName.startsWith("_")) {
           output.push({ funcName, jsdoc });
         }
       }