diff --git a/arduino-ide-extension/src/common/protocol/sketches-service.ts b/arduino-ide-extension/src/common/protocol/sketches-service.ts
index b82b9184e..767063aaf 100644
--- a/arduino-ide-extension/src/common/protocol/sketches-service.ts
+++ b/arduino-ide-extension/src/common/protocol/sketches-service.ts
@@ -205,7 +205,7 @@ export namespace Sketch {
     const validName = candidate
       ? candidate
           .replace(/^[^0-9a-zA-Z]{1}/g, defaultFallbackFirstChar)
-          .replace(/[^0-9a-zA-Z_\.-]/g, defaultFallbackChar)
+          .replace(/[^0-9a-zA-Z_]/g, defaultFallbackChar)
           .slice(0, 63)
       : defaultSketchFolderName;
     if (appendTimestampSuffix) {
@@ -233,7 +233,7 @@ export namespace Sketch {
     return candidate
       ? candidate
           .replace(/^[^0-9a-zA-Z]{1}/g, defaultFallbackFirstChar)
-          .replace(/[^0-9a-zA-Z_\.-]/g, defaultFallbackChar)
+          .replace(/[^0-9a-zA-Z_]/g, defaultFallbackChar)
           .slice(0, 36)
       : defaultSketchFolderName;
   }
diff --git a/arduino-ide-extension/src/test/common/sketches-service.test.ts b/arduino-ide-extension/src/test/common/sketches-service.test.ts
index 7671f70ad..4d74c316b 100644
--- a/arduino-ide-extension/src/test/common/sketches-service.test.ts
+++ b/arduino-ide-extension/src/test/common/sketches-service.test.ts
@@ -107,6 +107,9 @@ describe('sketch', () => {
       ['foo bar', 'foo_bar' + epochSuffix],
       ['.foobar', '0foobar' + epochSuffix],
       ['-fooBar', '0fooBar' + epochSuffix],
+      ['foobar.', 'foobar_' + epochSuffix],
+      ['fooBar-', 'fooBar_' + epochSuffix],
+      ['fooBar+', 'fooBar_' + epochSuffix],
       ['vAlid', 'vAlid' + epochSuffix],
     ].map(([input, expected]) =>
       toMapIt(input, expected, (input: string) =>
@@ -118,23 +121,20 @@ describe('sketch', () => {
   describe('toValidCloudSketchFolderName', () => {
     [
       ['sketch', 'sketch'],
-      [
-        'slash-and-dot-is-ok+but+no+plus.ino',
-        'slash-and-dot-is-ok_but_no_plus.ino',
-      ],
+      ['only_underscore-is+ok.ino', 'only_underscore_is_ok_ino'],
       ['regex++', 'regex__'],
-      ['dots...', 'dots...'],
-      ['.dots...', '0dots...'],
-      ['-dashes---', '0dashes---'],
+      ['dots...', 'dots___'],
+      ['.dots...', '0dots___'],
+      ['-dashes---', '0dashes___'],
       ['_underscore___', '0underscore___'],
       ['No Spaces', 'No_Spaces'],
       ['_startsWithUnderscore', '0startsWithUnderscore'],
-      ['Invalid+Char.ino', 'Invalid_Char.ino'],
+      ['Invalid+Char.ino', 'Invalid_Char_ino'],
       ['', 'sketch'],
       ['/', '0'],
       [
-        '//////////////////////////////////////-/',
-        '0___________________________________',
+        '/-1////////////////////+//////////////-/',
+        '0_1_________________________________',
       ],
       ['//trash/', '0_trash_'],
       [