diff --git a/src/Standards/PSR12/Sniffs/Classes/AnonClassDeclarationSniff.php b/src/Standards/PSR12/Sniffs/Classes/AnonClassDeclarationSniff.php
index db67fb9428..0e9197e354 100644
--- a/src/Standards/PSR12/Sniffs/Classes/AnonClassDeclarationSniff.php
+++ b/src/Standards/PSR12/Sniffs/Classes/AnonClassDeclarationSniff.php
@@ -97,7 +97,11 @@ public function process(File $phpcsFile, $stackPtr)
                 $first  = $phpcsFile->findFirstOnLine(T_WHITESPACE, $stackPtr, true);
                 $indent = str_repeat(' ', ($tokens[$first]['column'] - 1));
                 $phpcsFile->fixer->beginChangeset();
-                $phpcsFile->fixer->replaceToken(($prev + 1), '');
+
+                if ($tokens[($prev + 1)]['code'] === \T_WHITESPACE) {
+                    $phpcsFile->fixer->replaceToken(($prev + 1), '');
+                }
+
                 $phpcsFile->fixer->addNewline($prev);
                 $phpcsFile->fixer->addContentBefore($opener, $indent);
                 $phpcsFile->fixer->endChangeset();
diff --git a/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.inc b/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.inc
index e132b54df1..fe3ee02ef8 100644
--- a/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.inc
+++ b/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.inc
@@ -82,3 +82,9 @@ $foo->bar(
 
 foo(new class {
 });
+
+// Issue #3790: OpenBraceSameLine fixer should not remove open brace.
+$instance = new class() extends SomeClass implements
+    SomeInterface{
+    public function __construct() {}
+};
diff --git a/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.inc.fixed b/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.inc.fixed
index 921dcc02de..4a6c5a1f1a 100644
--- a/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.inc.fixed
+++ b/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.inc.fixed
@@ -84,3 +84,10 @@ $foo->bar(
 
 foo(new class {
 });
+
+// Issue #3790: OpenBraceSameLine fixer should not remove open brace.
+$instance = new class () extends SomeClass implements
+    SomeInterface
+{
+    public function __construct() {}
+};
diff --git a/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.php b/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.php
index cc162b290b..860ce0b797 100644
--- a/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.php
+++ b/src/Standards/PSR12/Tests/Classes/AnonClassDeclarationUnitTest.php
@@ -48,6 +48,8 @@ public function getErrorList()
             56 => 2,
             63 => 1,
             75 => 1,
+            87 => 1,
+            88 => 1,
         ];
 
     }//end getErrorList()