diff --git a/system/Database/BaseBuilder.php b/system/Database/BaseBuilder.php
index f87f21bf7308..0a720cf33036 100644
--- a/system/Database/BaseBuilder.php
+++ b/system/Database/BaseBuilder.php
@@ -658,34 +658,35 @@ protected function whereHaving(string $qbKey, $key, $value = null, string $type
 
                     $op = trim(current($op));
 
-                    if (substr($k, -1 * strlen($op)) === $op) {
-                        $k = rtrim(strrev(preg_replace(strrev('/' . $op . '/'), strrev(''), strrev($k), 1)));
+                    if (substr($k, -strlen($op)) === $op) {
+                        $k  = rtrim(substr($k, 0, -strlen($op)));
+                        $op = " {$op}";
+                    } else {
+                        $op = '';
                     }
-                }
-
-                $bind = $this->setBind($k, $v, $escape);
-
-                if (empty($op)) {
-                    $k .= ' =';
                 } else {
-                    $k .= " {$op}";
+                    $op = ' =';
                 }
 
                 if ($v instanceof Closure) {
                     $builder = $this->cleanClone();
-                    $v       = '(' . str_replace("\n", ' ', $v($builder)->getCompiledSelect()) . ')';
+                    $v       = ' (' . strtr($v($builder)->getCompiledSelect(), "\n", ' ') . ')';
                 } else {
-                    $v = " :{$bind}:";
+                    $bind = $this->setBind($k, $v, $escape);
+                    $v    = " :{$bind}:";
                 }
             } elseif (! $this->hasOperator($k) && $qbKey !== 'QBHaving') {
                 // value appears not to have been set, assign the test to IS NULL
-                $k .= ' IS NULL';
+                $op = ' IS NULL';
             } elseif (preg_match('/\s*(!?=|<>|IS(?:\s+NOT)?)\s*$/i', $k, $match, PREG_OFFSET_CAPTURE)) {
-                $k = substr($k, 0, $match[0][1]) . ($match[1][0] === '=' ? ' IS NULL' : ' IS NOT NULL');
+                $k  = substr($k, 0, $match[0][1]);
+                $op = $match[1][0] === '=' ? ' IS NULL' : ' IS NOT NULL';
+            } else {
+                $op = '';
             }
 
             $this->{$qbKey}[] = [
-                'condition' => $prefix . $k . $v,
+                'condition' => $prefix . $k . $op . $v,
                 'escape'    => $escape,
             ];
         }
@@ -841,7 +842,7 @@ protected function _whereIn(?string $key = null, $values = null, bool $not = fal
 
         if ($values instanceof Closure) {
             $builder = $this->cleanClone();
-            $ok      = str_replace("\n", ' ', $values($builder)->getCompiledSelect());
+            $ok      = strtr($values($builder)->getCompiledSelect(), "\n", ' ');
         } else {
             $whereIn = array_values($values);
             $ok      = $this->setBind($ok, $whereIn, $escape);
diff --git a/tests/system/Database/Builder/WhereTest.php b/tests/system/Database/Builder/WhereTest.php
index 653c837058aa..e58af53cadab 100644
--- a/tests/system/Database/Builder/WhereTest.php
+++ b/tests/system/Database/Builder/WhereTest.php
@@ -111,6 +111,22 @@ public function testWhereAssociateArray()
         $this->assertSame($expectedBinds, $builder->getBinds());
     }
 
+    public function testWhereAssociateArrayKeyHasEqualValueIsNull()
+    {
+        $builder = $this->db->table('users');
+
+        $where = [
+            'deleted_at =' => null,
+        ];
+
+        $expectedSQL   = 'SELECT * FROM "users" WHERE "deleted_at" IS NULL';
+        $expectedBinds = [];
+
+        $builder->where($where);
+        $this->assertSame($expectedSQL, str_replace("\n", ' ', $builder->getCompiledSelect()));
+        $this->assertSame($expectedBinds, $builder->getBinds());
+    }
+
     public function testWhereCustomString()
     {
         $builder = $this->db->table('jobs');