diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4ab0156be0..504590d55b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -157,6 +157,8 @@ The file documents changes to the PHP_CodeSniffer project.
     - Thanks to @simonsan for the patch
 - Fixed bug #3893 : Generic/DocComment : the SpacingAfterTagGroup fixer could accidentally remove ignore annotations
     - Thanks to Juliette Reinders Folmer (@jrfnl) for the patch
+- Fixed bug #3904 : Squiz/FunctionSpacing : prevent potential fixer conflict
+    - Thanks to Juliette Reinders Folmer (@jrfnl) for the patch
 - Fixed bug #3906 : Tokenizer/CSS: fixed a bug related to the unsupported slash comment syntax
     - Thanks to Dan Wallis (@fredden) for the patch
 
diff --git a/src/Standards/Squiz/Sniffs/WhiteSpace/FunctionSpacingSniff.php b/src/Standards/Squiz/Sniffs/WhiteSpace/FunctionSpacingSniff.php
index 32af8b4ca0..dc99d73f6c 100644
--- a/src/Standards/Squiz/Sniffs/WhiteSpace/FunctionSpacingSniff.php
+++ b/src/Standards/Squiz/Sniffs/WhiteSpace/FunctionSpacingSniff.php
@@ -262,22 +262,21 @@ public function process(File $phpcsFile, $stackPtr)
                 $prevContent = $phpcsFile->findPrevious(T_WHITESPACE, ($tokens[$prevContent]['comment_opener'] - 1), null, true);
             }
 
-            $prevLineToken = $prevContent;
-
             // Before we throw an error, check that we are not throwing an error
             // for another function. We don't want to error for no blank lines after
             // the previous function and no blank lines before this one as well.
-            $prevLine   = ($tokens[$prevContent]['line'] - 1);
-            $i          = ($stackPtr - 1);
-            $foundLines = 0;
-
             $stopAt = 0;
-            if (isset($tokens[$stackPtr]['conditions']) === true) {
-                $conditions = $tokens[$stackPtr]['conditions'];
+            if (isset($tokens[$prevLineToken]['conditions']) === true) {
+                $conditions = $tokens[$prevLineToken]['conditions'];
                 $conditions = array_keys($conditions);
                 $stopAt     = array_pop($conditions);
             }
 
+            $prevLineToken = $prevContent;
+            $prevLine      = ($tokens[$prevContent]['line'] - 1);
+            $i          = ($stackPtr - 1);
+            $foundLines = 0;
+
             while ($currentLine !== $prevLine && $currentLine > 1 && $i > $stopAt) {
                 if ($tokens[$i]['code'] === T_FUNCTION) {
                     // Found another interface or abstract function.
diff --git a/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.1.inc b/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.1.inc
index 36a287f077..b03a0ed82c 100644
--- a/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.1.inc
+++ b/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.1.inc
@@ -574,3 +574,11 @@ class ClassWithAttributes {
 // phpcs:set Squiz.WhiteSpace.FunctionSpacing spacing 2
 // phpcs:set Squiz.WhiteSpace.FunctionSpacing spacingBeforeFirst 2
 // phpcs:set Squiz.WhiteSpace.FunctionSpacing spacingAfterLast 2
+
+// Issue #3904.
+echo 'this line belongs with the #3904 test';
+class Person {public function __construct($name){}}
+echo 'this line belongs with the #3904 test';
+
+function Foo() {} function bar($name){}
+echo 'this line belongs with the #3904 test';
diff --git a/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.1.inc.fixed b/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.1.inc.fixed
index ac2df1cb7b..443824ca14 100644
--- a/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.1.inc.fixed
+++ b/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.1.inc.fixed
@@ -656,3 +656,18 @@ class ClassWithAttributes {
 // phpcs:set Squiz.WhiteSpace.FunctionSpacing spacing 2
 // phpcs:set Squiz.WhiteSpace.FunctionSpacing spacingBeforeFirst 2
 // phpcs:set Squiz.WhiteSpace.FunctionSpacing spacingAfterLast 2
+
+// Issue #3904.
+echo 'this line belongs with the #3904 test';
+
+
+class Person {public function __construct($name){}}
+
+
+echo 'this line belongs with the #3904 test';
+
+
+function Foo() {} function bar($name){}
+
+
+echo 'this line belongs with the #3904 test';
diff --git a/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.php b/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.php
index 2a3107c75e..307d481d5f 100644
--- a/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.php
+++ b/src/Standards/Squiz/Tests/WhiteSpace/FunctionSpacingUnitTest.php
@@ -95,6 +95,8 @@ public function getErrorList($testFile='')
                 553 => 1,
                 560 => 1,
                 566 => 1,
+                580 => 2,
+                583 => 3,
             ];
 
         case 'FunctionSpacingUnitTest.2.inc':