diff --git a/lib/helpers/populate/getModelsMapForPopulate.js b/lib/helpers/populate/getModelsMapForPopulate.js
index 7d1b3f47fd..05d91847ae 100644
--- a/lib/helpers/populate/getModelsMapForPopulate.js
+++ b/lib/helpers/populate/getModelsMapForPopulate.js
@@ -239,7 +239,7 @@ module.exports = function getModelsMapForPopulate(model, docs, options) {
       modelNames = [modelNameFromQuery]; // query options
     } else if (refPath != null) {
       if (typeof refPath === 'function') {
-        const subdocPath = options.path.slice(0, options.path.length - schema.path.length - 1);
+        const subdocPath = options.path.slice(0, Math.max(0, options.path.length - schema.path.length - 1));
         const vals = mpath.get(subdocPath, doc, lookupLocalFields);
         const subdocsBeingPopulated = Array.isArray(vals) ?
           utils.array.flatten(vals) :
@@ -301,7 +301,7 @@ module.exports = function getModelsMapForPopulate(model, docs, options) {
           // Ensure correct context for ref functions: subdoc, not top-level doc. See gh-8469
           modelNames = new Set();
 
-          const subdocPath = options.path.slice(0, options.path.length - schemaForCurrentDoc.path.length - 1);
+          const subdocPath = options.path.slice(0, Math.max(0, options.path.length - schemaForCurrentDoc.path.length - 1));
           const vals = mpath.get(subdocPath, doc, lookupLocalFields);
           const subdocsBeingPopulated = Array.isArray(vals) ?
             utils.array.flatten(vals) :
@@ -322,7 +322,7 @@ module.exports = function getModelsMapForPopulate(model, docs, options) {
       } else if ((schemaForCurrentDoc = get(schema, 'options.refPath')) != null) {
         isRefPath = true;
         if (typeof refPath === 'function') {
-          const subdocPath = options.path.slice(0, options.path.length - schemaForCurrentDoc.path.length - 1);
+          const subdocPath = options.path.slice(0, Math.max(0, options.path.length - schemaForCurrentDoc.path.length - 1));
           const vals = mpath.get(subdocPath, doc, lookupLocalFields);
           const subdocsBeingPopulated = Array.isArray(vals) ?
             utils.array.flatten(vals) :