diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 352738be6..d831aaf88 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -34,6 +34,8 @@ jobs:
       MYSQL_PASSWORD: "zftest"
       MYSQL_DATABASE: "zftest"
       MYSQL_HOST: "127.0.0.1"
+      # Default locales are: C C.UTF-8 POSIX en_US.utf8
+      LOCALES: "fr_FR@euro fr_FR fr_BE.UTF-8 de en_US"
 
     services:
       memcache:
@@ -81,6 +83,11 @@ jobs:
       - name: Setup environment for PHPUnit
         run: |
           cp tests/TestConfiguration.ci.php tests/TestConfiguration.php
+          echo "Existing locales"
+          locale -a
+          sudo apt-get update && sudo apt-get install tzdata locales -y && sudo locale-gen $LOCALES
+          echo "All languages..."
+          locale -a
 
       - name: "Run PHPUnit tests (Experimental: ${{ matrix.experimental }})"
         env:
diff --git a/tests/Zend/Locale/FormatTest.php b/tests/Zend/Locale/FormatTest.php
index 39ac8f790..ef9f6fdc3 100644
--- a/tests/Zend/Locale/FormatTest.php
+++ b/tests/Zend/Locale/FormatTest.php
@@ -35,6 +35,12 @@
  */
 class Zend_Locale_FormatTest extends PHPUnit_Framework_TestCase
 {
+    /**
+     * Constant for Non-breaking space UTF-8 encoded value.
+     * https://en.wikipedia.org/wiki/Non-breaking_space
+     */
+    const NBSP = "\xC2\xA0";
+
     /**
      * teardown / cleanup
      */
@@ -934,19 +940,29 @@ public function testConvertPhpToIso()
      */
     public function testToFloatSetlocale()
     {
-        setlocale(LC_ALL, 'fr_FR@euro'); // test setup
-
-        //var_dump( setlocale(LC_NUMERIC, '0')); // this is the specific setting of interest
-        $locale_fr = new Zend_Locale('fr_FR');
-        $locale_en = new Zend_Locale('en_US');
-        $params_fr = array('precision' => 2, 'locale' => $locale_fr);
-        $params_en = array('precision' => 2, 'locale' => $locale_en);
-        $myFloat = 1234.5;
-        $test1 = Zend_Locale_Format::toFloat($myFloat, $params_fr);
-        $test2 = Zend_Locale_Format::toFloat($myFloat, $params_en);
-        $this->assertEquals("1 234,50", $test1);
-        $this->assertEquals("1,234.50", $test2);
-        // placing tearDown here (i.e. restoring locale) won't work, if test already failed/aborted above.
+        $locale = setlocale(LC_ALL, 0);
+        try {
+            setlocale(LC_ALL, 'fr_FR@euro');
+
+            $locale_fr = new Zend_Locale('fr_FR');
+            $locale_en = new Zend_Locale('en_US');
+            $params_fr = array('precision' => 2, 'locale' => $locale_fr);
+            $params_en = array('precision' => 2, 'locale' => $locale_en);
+            $myFloat = 1234.5;
+            $test1 = Zend_Locale_Format::toFloat($myFloat, $params_fr);
+            $test2 = Zend_Locale_Format::toFloat($myFloat, $params_en);
+
+            $this->assertEquals("1" . self::NBSP . "234,50", $test1);
+            $this->assertEquals("1,234.50", $test2);
+
+        } catch (Exception $e) {
+            setlocale(LC_ALL, $locale);
+            throw $e;
+        } catch (Throwable $e) {
+            setlocale(LC_ALL, $locale);
+            throw $e;
+        }
+        setlocale(LC_ALL, $locale);
     }
 
     /**
@@ -1107,14 +1123,19 @@ public function testToNumberWithoutFormatWithPrecision()
      */
     public function testCheckDateFormatDoesNotEmitNoticeWhenNoOptionsAreNotProvided()
     {
+        $locale = setlocale(LC_ALL, 0); // read current locale
         try {
             setlocale(LC_ALL, 'en_US'); // test setup
             Zend_Locale_Format::setOptions(array('date_format' => 'yyyy-MM-dd'));
+            $checkDateFormat = Zend_Locale_Format::checkDateFormat('2011-10-21', array());
 
-            $this->assertTrue(Zend_Locale_Format::checkDateFormat('2011-10-21', array()));
+            $this->assertTrue($checkDateFormat);
         } catch ( PHPUnit_Framework_Error_Notice $ex ) {
+            setlocale(LC_ALL, $locale); // restore previous locale
+
             $this->fail('Zend_Locale_Format::checkDateFormat emitted unexpected E_NOTICE');
         }
+        setlocale(LC_ALL, $locale); // restore previous locale
     }
 
     /**
diff --git a/tests/Zend/Validate/FloatTest.php b/tests/Zend/Validate/FloatTest.php
index 26a4386c8..e09ce128b 100644
--- a/tests/Zend/Validate/FloatTest.php
+++ b/tests/Zend/Validate/FloatTest.php
@@ -35,6 +35,12 @@
  */
 class Zend_Validate_FloatTest extends PHPUnit_Framework_TestCase
 {
+    /**
+     * Constant for Non-breaking space UTF-8 encoded value.
+     * https://en.wikipedia.org/wiki/Non-breaking_space
+     */
+    const NBSP = "\xC2\xA0";
+
     /**
      * Zend_Validate_Float object
      *
@@ -42,6 +48,11 @@ class Zend_Validate_FloatTest extends PHPUnit_Framework_TestCase
      */
     protected $_validator;
 
+    /**
+     * @var string
+     */
+    private $_locale;
+
     /**
      * Creates a new Zend_Validate_Float object for each test method
      *
@@ -136,10 +147,14 @@ public function testUsingApplicationLocale()
      */
     public function testNoZendLocaleButPhpLocale()
     {
+        $locale = setlocale(LC_ALL, 0);
         setlocale(LC_ALL, 'de');
         $valid = new Zend_Validate_Float();
-        $this->assertTrue($valid->isValid(123,456));
-        $this->assertTrue($valid->isValid('123,456'));
+        $isValid1 = $valid->isValid(123.456);
+        $isValid2 = $valid->isValid('123,456');
+        setlocale(LC_ALL, $locale);
+        $this->assertTrue($isValid1);
+        $this->assertTrue($isValid2);
     }
 
     /**
@@ -157,9 +172,12 @@ public function testLocaleDeFloatType()
      */
     public function testPhpLocaleDeFloatType()
     {
+        $locale = setlocale(LC_ALL, 0);
         setlocale(LC_ALL, 'de');
         $valid = new Zend_Validate_Float();
-        $this->assertTrue($valid->isValid(10.5));
+        $isValid = $valid->isValid(10.5);
+        setlocale(LC_ALL, $locale);
+        $this->assertTrue($isValid);
     }
 
     /**
@@ -167,9 +185,12 @@ public function testPhpLocaleDeFloatType()
      */
     public function testPhpLocaleFrFloatType()
     {
+        $locale = setlocale(LC_ALL, 0);
         setlocale(LC_ALL, 'fr');
         $valid = new Zend_Validate_Float();
-        $this->assertTrue($valid->isValid(10.5));
+        $isValid = $valid->isValid(10.5);
+        setlocale(LC_ALL, $locale);
+        $this->assertTrue($isValid);
     }
 
     /**
@@ -177,15 +198,25 @@ public function testPhpLocaleFrFloatType()
      */
     public function testPhpLocaleDeStringType()
     {
+        $lcAll = setlocale(LC_ALL, 0);
         setlocale(LC_ALL, 'de_AT');
+        $lcNumeric = setlocale(LC_NUMERIC, 0);
         setlocale(LC_NUMERIC, 'de_AT');
         $valid = new Zend_Validate_Float('de_AT');
-        $this->assertTrue($valid->isValid('1,3'));
-        $this->assertTrue($valid->isValid('1000,3'));
-        $this->assertTrue($valid->isValid('1.000,3'));
-        $this->assertFalse($valid->isValid('1.3'));
-        $this->assertFalse($valid->isValid('1000.3'));
-        $this->assertFalse($valid->isValid('1,000.3'));
+        $isValid0 = $valid->isValid('1,3');
+        $isValid1 = $valid->isValid('1000,3');
+        $isValid2 = $valid->isValid('1.000,3');
+        $isValid3 = $valid->isValid('1.3');
+        $isValid4 = $valid->isValid('1000.3');
+        $isValid5 = $valid->isValid('1,000.3');
+        setlocale(LC_ALL, $lcAll);
+        setlocale(LC_NUMERIC, $lcNumeric);
+        $this->assertTrue($isValid0);
+        $this->assertTrue($isValid1);
+        $this->assertTrue($isValid2);
+        $this->assertFalse($isValid3);
+        $this->assertFalse($isValid4);
+        $this->assertFalse($isValid5);
     }
 
     /**
@@ -196,7 +227,7 @@ public function testPhpLocaleFrStringType()
         $valid = new Zend_Validate_Float('fr_FR');
         $this->assertTrue($valid->isValid('1,3'));
         $this->assertTrue($valid->isValid('1000,3'));
-        $this->assertTrue($valid->isValid('1 000,3'));
+        $this->assertTrue($valid->isValid('1' . self::NBSP . '000,3'));
         $this->assertFalse($valid->isValid('1.3'));
         $this->assertFalse($valid->isValid('1000.3'));
         $this->assertFalse($valid->isValid('1,000.3'));