diff --git a/src/configuration/configuration.ts b/src/configuration/configuration.ts
index 9e881786333..b777e1719c8 100644
--- a/src/configuration/configuration.ts
+++ b/src/configuration/configuration.ts
@@ -101,7 +101,7 @@ class Configuration implements IConfiguration {
 
       const modeKeyBindingsMap = new Map<string, IKeyRemapping>();
       for (let i = keybindings.length - 1; i >= 0; i--) {
-        let remapping = keybindings[i];
+        let remapping = keybindings[i] as IKeyRemapping;
 
         // validate
         let remappingErrors = await configurationValidator.isRemappingValid(remapping);
diff --git a/src/configuration/configurationValidator.ts b/src/configuration/configurationValidator.ts
index dd0bee081ae..bc348c7c4f6 100644
--- a/src/configuration/configurationValidator.ts
+++ b/src/configuration/configurationValidator.ts
@@ -42,6 +42,18 @@ class ConfigurationValidator {
       return [{ level: 'error', message: `${remapping.before} missing 'after' key or 'command'.` }];
     }
 
+    if (!(remapping.before instanceof Array)) {
+      return [
+        { level: 'error', message: `Remapping of '${remapping.before}' should be a string array.` },
+      ];
+    }
+
+    if (remapping.after && !(remapping.after instanceof Array)) {
+      return [
+        { level: 'error', message: `Remapping of '${remapping.after}' should be a string array.` },
+      ];
+    }
+
     if (remapping.commands) {
       for (const command of remapping.commands) {
         let cmd: string;
diff --git a/src/configuration/remapper.ts b/src/configuration/remapper.ts
index 96507cb2b44..f26d805a148 100644
--- a/src/configuration/remapper.ts
+++ b/src/configuration/remapper.ts
@@ -197,7 +197,7 @@ export class Remapper implements IRemapper {
     for (let sliceLength = startingSliceLength; sliceLength >= range[0]; sliceLength--) {
       const keySlice = inputtedKeys.slice(-sliceLength).join('');
 
-      this._logger.verbose(`trying to find matching remap for keySlice=${keySlice}.`);
+      this._logger.verbose(`key=${inputtedKeys}. keySlice=${keySlice}.`);
       if (userDefinedRemappings.has(keySlice)) {
         // In Insert mode, we allow users to precede remapped commands
         // with extraneous keystrokes (eg. "hello world jj")
@@ -208,6 +208,7 @@ export class Remapper implements IRemapper {
             .slice(0, inputtedKeys.length - keySlice.length)
             .join('');
           if (precedingKeys.length > 0 && !/^[0-9]+$/.test(precedingKeys)) {
+            this._logger.verbose(`key sequences need to match precisely. precedingKeys=${precedingKeys}.`);
             break;
           }
         }