diff --git a/Zend/Optimizer/zend_ssa.c b/Zend/Optimizer/zend_ssa.c
index fec5609d46e..47202ab755c 100644
--- a/Zend/Optimizer/zend_ssa.c
+++ b/Zend/Optimizer/zend_ssa.c
@@ -284,6 +284,14 @@ static void place_essa_pis(
 			default:
 				continue;
 		}
+
+		/* The following patterns all inspect the opline directly before the JMPZ opcode.
+		 * Make sure that it is part of the same block, otherwise it might not be a dominating
+		 * assignment. */
+		if (blocks[j].len == 1) {
+			continue;
+		}
+
 		if (opline->op1_type == IS_TMP_VAR &&
 		    ((opline-1)->opcode == ZEND_IS_EQUAL ||
 		     (opline-1)->opcode == ZEND_IS_NOT_EQUAL ||
diff --git a/ext/opcache/tests/bug81015.phpt b/ext/opcache/tests/bug81015.phpt
new file mode 100644
index 00000000000..b5009e6a236
--- /dev/null
+++ b/ext/opcache/tests/bug81015.phpt
@@ -0,0 +1,26 @@
+--TEST--
+Bug #81015: Opcache optimization assumes wrong part of ternary operator in if-condition
+--FILE--
+<?php
+
+function ternary(bool $enabled, ?string $value): void
+{
+	// the "true" part is not as trivial in the real case
+	if ($enabled ? true : $value === null) {
+		echo ($value ?? 'NULL') . "\n";
+	} else {
+		echo "INVALID\n";
+	}
+}
+
+ternary(true, 'value');
+ternary(true, null);
+ternary(false, 'value');
+ternary(false, null);
+
+?>
+--EXPECT--
+value
+NULL
+INVALID
+NULL