diff --git a/phpunit/code/loop/for-loop-post-expr-opt.php b/phpunit/code/loop/for-loop-post-expr-opt.php
index 1679311b..64615ddd 100644
--- a/phpunit/code/loop/for-loop-post-expr-opt.php
+++ b/phpunit/code/loop/for-loop-post-expr-opt.php
@@ -58,40 +58,34 @@ class StaticCounter {
 
 function test_property_post_inc_not_rewritten(): void {
     $obj = new Counter();
-    for ($i = 0; $i < 10; $i++) {
-        $obj->value++;
+    for ($i = 0; $i < 10; $i++, $obj->value++) {
     }
 }
 
 function test_property_post_dec_not_rewritten(): void {
     $obj = new Counter();
-    for ($i = 0; $i < 10; $i++) {
-        $obj->value--;
+    for ($i = 0; $i < 10; $i++, $obj->value--) {
     }
 }
 
 function test_static_property_post_inc_not_rewritten(): void {
-    for ($i = 0; $i < 10; $i++) {
-        StaticCounter::$count++;
+    for ($i = 0; $i < 10; $i++, StaticCounter::$count++) {
     }
 }
 
 function test_static_property_post_dec_not_rewritten(): void {
-    for ($i = 0; $i < 10; $i++) {
-        StaticCounter::$count--;
+    for ($i = 0; $i < 10; $i++, StaticCounter::$count--) {
     }
 }
 
 function test_array_element_post_inc_not_rewritten(): void {
     $arr = [0, 0, 0];
-    for ($i = 0; $i < 10; $i++) {
-        $arr[$i % 3]++;
+    for ($i = 0; $i < 10; $i++, $arr[$i % 3]++) {
     }
 }
 
 function test_array_element_post_dec_not_rewritten(): void {
     $arr = [10, 10, 10];
-    for ($i = 0; $i < 10; $i++) {
-        $arr[$i % 3]--;
+    for ($i = 0; $i < 10; $i++, $arr[$i % 3]--) {
     }
 }
diff --git a/phpunit/code/loop/for-loop-undefined-post-dec.php b/phpunit/code/loop/for-loop-undefined-post-dec.php
new file mode 100644
index 00000000..066c84f9
--- /dev/null
+++ b/phpunit/code/loop/for-loop-undefined-post-dec.php
@@ -0,0 +1,7 @@
+<?php
+
+function main(): void
+{
+    for (; false; $i--) {
+    }
+}
diff --git a/phpunit/code/loop/for-loop-undefined-post-inc.php b/phpunit/code/loop/for-loop-undefined-post-inc.php
new file mode 100644
index 00000000..5397b533
--- /dev/null
+++ b/phpunit/code/loop/for-loop-undefined-post-inc.php
@@ -0,0 +1,7 @@
+<?php
+
+function main(): void
+{
+    for (; false; $i++) {
+    }
+}
diff --git a/phpunit/code/undefined-pre-dec.php b/phpunit/code/undefined-pre-dec.php
new file mode 100644
index 00000000..be1f8eba
--- /dev/null
+++ b/phpunit/code/undefined-pre-dec.php
@@ -0,0 +1,6 @@
+<?php
+
+function main(): void
+{
+    --$value;
+}
diff --git a/phpunit/code/undefined-pre-inc.php b/phpunit/code/undefined-pre-inc.php
new file mode 100644
index 00000000..43f71ba3
--- /dev/null
+++ b/phpunit/code/undefined-pre-inc.php
@@ -0,0 +1,6 @@
+<?php
+
+function main(): void
+{
+    ++$value;
+}
diff --git a/phpunit/src/AssignOpTest.php b/phpunit/src/AssignOpTest.php
index 4aa1c8db..50c68d32 100644
--- a/phpunit/src/AssignOpTest.php
+++ b/phpunit/src/AssignOpTest.php
@@ -26,4 +26,14 @@ class AssignOpTest extends \BaseTest
     {
         $this->exec('Cannot use -- on php::Decimal', 'decimal-pre-dec.php');
     }
+
+    public function testPreIncrementUndefinedVar(): void
+    {
+        $this->exec('The variable `$value` is undefined', 'undefined-pre-inc.php');
+    }
+
+    public function testPreDecrementUndefinedVar(): void
+    {
+        $this->exec('The variable `$value` is undefined', 'undefined-pre-dec.php');
+    }
 }
diff --git a/phpunit/src/LoopControlTest.php b/phpunit/src/LoopControlTest.php
index e80a0073..48acac18 100644
--- a/phpunit/src/LoopControlTest.php
+++ b/phpunit/src/LoopControlTest.php
@@ -61,4 +61,20 @@ class LoopControlTest extends \BaseTest
         $this->assertMatchesRegularExpression('/\.item\([^)]+\)[^;]*\+\+/', $cpp);
         $this->assertMatchesRegularExpression('/\.item\([^)]+\)[^;]*--/', $cpp);
     }
+
+    public function testForLoopUndefinedPostIncrementKeepsCompilerDiagnostic(): void
+    {
+        $this->exec(
+            'The variable `$i` is undefined',
+            'loop/for-loop-undefined-post-inc.php',
+        );
+    }
+
+    public function testForLoopUndefinedPostDecrementKeepsCompilerDiagnostic(): void
+    {
+        $this->exec(
+            'The variable `$i` is undefined',
+            'loop/for-loop-undefined-post-dec.php',
+        );
+    }
 }
diff --git a/src/CompilerBase.php b/src/CompilerBase.php
index cac3c1e6..bdd58a52 100644
--- a/src/CompilerBase.php
+++ b/src/CompilerBase.php
@@ -3350,8 +3350,11 @@ class CompilerBase implements PropertyAccessContext
         if ($type === Type::BIGINT || $type === Type::DECIMAL || $type === Type::BIGFLOAT) {
             $this->fatalError($expr, 'Cannot use ++ on ' . $type . '. Use += 1 instead (Big* types are immutable).');
         }
-        $result = '++' . $this->parseWritableIdentifier($expr->var);
-        return $result;
+        $var = $this->parseWritableIdentifier($expr->var);
+        if ($this->isVarExpr($expr->var) && !$this->hasVar($var)) {
+            $this->errorUndefinedVariable($expr->var);
+        }
+        return '++' . $var;
     }
 
     /**
@@ -3789,8 +3792,11 @@ class CompilerBase implements PropertyAccessContext
         if ($type === Type::BIGINT || $type === Type::DECIMAL || $type === Type::BIGFLOAT) {
             $this->fatalError($expr, 'Cannot use -- on ' . $type . '. Use -= 1 instead (Big* types are immutable).');
         }
-        $result = '--' . $this->parseWritableIdentifier($expr->var);
-        return $result;
+        $var = $this->parseWritableIdentifier($expr->var);
+        if ($this->isVarExpr($expr->var) && !$this->hasVar($var)) {
+            $this->errorUndefinedVariable($expr->var);
+        }
+        return '--' . $var;
     }
 
     protected function parsePrint(Expr\Print_ $expr): string
diff --git a/tests/compiler/loop/for-post-expression-inc-dec.phpt b/tests/compiler/loop/for-post-expression-inc-dec.phpt
new file mode 100644
index 00000000..00e3f746
--- /dev/null
+++ b/tests/compiler/loop/for-post-expression-inc-dec.phpt
@@ -0,0 +1,51 @@
+--TEST--
+for post-expression increment and decrement preserve runtime semantics
+--FILE--
+<?php
+
+final class LoopCounter
+{
+    public int $value = 0;
+    public static int $staticValue = 10;
+}
+
+function ascending(mixed $start): void
+{
+    for ($i = $start; $i < 3; $i++) {
+        echo $i;
+    }
+    echo ':', $i, "\n";
+}
+
+function descending(mixed $start): void
+{
+    for ($i = $start; $i > 0; $i--) {
+        echo $i;
+    }
+    echo ':', $i, "\n";
+}
+
+function main(): void
+{
+    ascending(0);
+    descending(3);
+
+    $object = new LoopCounter();
+    $values = [0];
+    for (
+        $i = 0;
+        $i < 3;
+        $i++, $object->value++, LoopCounter::$staticValue--, $values[0]++
+    ) {
+    }
+
+    var_dump($i, $object->value, LoopCounter::$staticValue, $values[0]);
+}
+?>
+--EXPECT--
+012:3
+321:0
+int(3)
+int(3)
+int(7)
+int(3)