diff --git a/src/Standards/PSR12/Sniffs/Functions/ReturnTypeDeclarationSniff.php b/src/Standards/PSR12/Sniffs/Functions/ReturnTypeDeclarationSniff.php
index b0c610edb7..f783b691d4 100644
--- a/src/Standards/PSR12/Sniffs/Functions/ReturnTypeDeclarationSniff.php
+++ b/src/Standards/PSR12/Sniffs/Functions/ReturnTypeDeclarationSniff.php
@@ -61,29 +61,35 @@ public function process(File $phpcsFile, int $stackPtr)
             $returnType = $phpcsFile->findPrevious(T_NULLABLE, ($returnType - 1));
         }
 
+        $colon = $phpcsFile->findPrevious(T_COLON, ($returnType - 1), $tokens[$stackPtr]['parenthesis_closer']);
+        if ($colon === false) {
+            // Parse error / live coding.
+            return;
+        }
+
         if ($tokens[($returnType - 1)]['code'] !== T_WHITESPACE
             || $tokens[($returnType - 1)]['content'] !== ' '
-            || $tokens[($returnType - 2)]['code'] !== T_COLON
+            || ($returnType - 2) !== $colon
         ) {
             $error = 'There must be a single space between the colon and type in a return type declaration';
-            if ($tokens[($returnType - 1)]['code'] === T_WHITESPACE
-                && $tokens[($returnType - 2)]['code'] === T_COLON
-            ) {
-                $fix = $phpcsFile->addFixableError($error, $returnType, 'SpaceBeforeReturnType');
-                if ($fix === true) {
-                    $phpcsFile->fixer->replaceToken(($returnType - 1), ' ');
-                }
-            } elseif ($tokens[($returnType - 1)]['code'] === T_COLON) {
+
+            $nonWhitespaceToken = $phpcsFile->findNext(T_WHITESPACE, ($colon + 1), $returnType, true);
+            if ($nonWhitespaceToken !== false) {
+                $phpcsFile->addError($error, $returnType, 'SpaceBeforeReturnType');
+            } else {
                 $fix = $phpcsFile->addFixableError($error, $returnType, 'SpaceBeforeReturnType');
                 if ($fix === true) {
+                    $phpcsFile->fixer->beginChangeset();
+                    for ($i = ($returnType - 1); $i > $colon; $i--) {
+                        $phpcsFile->fixer->replaceToken($i, '');
+                    }
+
                     $phpcsFile->fixer->addContentBefore($returnType, ' ');
+                    $phpcsFile->fixer->endChangeset();
                 }
-            } else {
-                $phpcsFile->addError($error, $returnType, 'SpaceBeforeReturnType');
             }
         }
 
-        $colon = $phpcsFile->findPrevious(T_COLON, $returnType);
         if ($tokens[($colon - 1)]['code'] !== T_CLOSE_PARENTHESIS) {
             $error = 'There must not be a space before the colon in a return type declaration';
             $prev  = $phpcsFile->findPrevious(T_WHITESPACE, ($colon - 1), null, true);
diff --git a/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.inc b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.1.inc
similarity index 91%
rename from src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.inc
rename to src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.1.inc
index 59ab1aa785..78c4b953a8 100644
--- a/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.inc
+++ b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.1.inc
@@ -64,3 +64,11 @@ function functionName(?string $arg1, ?int &$arg2):
 fn (?\DateTime $arg) : ?\DateTime => $arg;
 
 return (!$a ? [ new class { public function b(): c {} } ] : []);
+
+// This should be fixed in one fixer loop iteration.
+function multipleWhitespaceTokens():
+
+
+
+
+    ?int {}
diff --git a/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.inc.fixed b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.1.inc.fixed
similarity index 92%
rename from src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.inc.fixed
rename to src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.1.inc.fixed
index cd79f78163..5c3c03d3ea 100644
--- a/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.inc.fixed
+++ b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.1.inc.fixed
@@ -60,3 +60,6 @@ function functionName(?string $arg1, ?int &$arg2): ?string {}
 fn (?\DateTime $arg): ?\DateTime => $arg;
 
 return (!$a ? [ new class { public function b(): c {} } ] : []);
+
+// This should be fixed in one fixer loop iteration.
+function multipleWhitespaceTokens(): ?int {}
diff --git a/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.2.inc b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.2.inc
new file mode 100644
index 0000000000..e1029fa0be
--- /dev/null
+++ b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.2.inc
@@ -0,0 +1,4 @@
+<?php
+
+// Intentional parse error. There should be a colon between the function parameters and its return type.
+$closure = function () null { return null; };
diff --git a/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.3.inc b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.3.inc
new file mode 100644
index 0000000000..98788b3294
--- /dev/null
+++ b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.3.inc
@@ -0,0 +1,4 @@
+<?php
+
+// Intentional parse error. There should be a colon between the function 'use' and its return type.
+$closure = function ($foo) use ($bar) string { return 'baz'; };
diff --git a/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.4.inc b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.4.inc
new file mode 100644
index 0000000000..4fe5b79086
--- /dev/null
+++ b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.4.inc
@@ -0,0 +1,4 @@
+<?php
+
+// Intentional parse error. There should be a colon between the function parameters and its return type.
+function foo($obj = new DateTime(datetime: "now")) null {}
diff --git a/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.php b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.php
index 48f56cf990..dbbf2bb6bf 100644
--- a/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.php
+++ b/src/Standards/PSR12/Tests/Functions/ReturnTypeDeclarationUnitTest.php
@@ -27,24 +27,32 @@ final class ReturnTypeDeclarationUnitTest extends AbstractSniffTestCase
      * The key of the array should represent the line number and the value
      * should represent the number of errors that should occur on that line.
      *
+     * @param string $testFile The name of the file being tested.
+     *
      * @return array<int, int>
      */
-    protected function getErrorList()
+    protected function getErrorList($testFile = '')
     {
-        return [
-            27 => 1,
-            28 => 1,
-            35 => 2,
-            41 => 2,
-            48 => 2,
-            52 => 1,
-            55 => 1,
-            56 => 1,
-            59 => 1,
-            60 => 1,
-            62 => 1,
-            64 => 1,
-        ];
+        switch ($testFile) {
+            case 'ReturnTypeDeclarationUnitTest.1.inc':
+                return [
+                    27 => 1,
+                    28 => 1,
+                    35 => 2,
+                    41 => 2,
+                    48 => 2,
+                    52 => 1,
+                    55 => 1,
+                    56 => 1,
+                    59 => 1,
+                    60 => 1,
+                    62 => 1,
+                    64 => 1,
+                    74 => 1,
+                ];
+            default:
+                return [];
+        }
     }
 
 
@@ -54,9 +62,11 @@ protected function getErrorList()
      * The key of the array should represent the line number and the value
      * should represent the number of warnings that should occur on that line.
      *
+     * @param string $testFile The name of the file being tested.
+     *
      * @return array<int, int>
      */
-    protected function getWarningList()
+    protected function getWarningList($testFile = '')
     {
         return [];
     }