diff --git a/src/Type/ArrayType.php b/src/Type/ArrayType.php
index 76e5392f50..b8487cde25 100644
--- a/src/Type/ArrayType.php
+++ b/src/Type/ArrayType.php
@@ -176,6 +176,9 @@ public function getIterableKeyType(): Type
 		if ($keyType instanceof MixedType && !$keyType instanceof TemplateMixedType) {
 			return new BenevolentUnionType([new IntegerType(), new StringType()]);
 		}
+		if ($keyType instanceof StrictMixedType) {
+			return new BenevolentUnionType([new IntegerType(), new StringType()]);
+		}
 
 		return $keyType;
 	}
diff --git a/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php b/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
index 6d0dd8a99d..2103a67369 100644
--- a/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
+++ b/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
@@ -876,4 +876,15 @@ public function testBug5661(): void
 		$this->analyse([__DIR__ . '/data/bug-5661.php'], []);
 	}
 
+	public function testBug5872(): void
+	{
+		$this->checkExplicitMixed = true;
+		$this->analyse([__DIR__ . '/data/bug-5872.php'], [
+			[
+				'Parameter #2 $array of function array_map expects array, mixed given.',
+				12,
+			],
+		]);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Functions/data/bug-5872.php b/tests/PHPStan/Rules/Functions/data/bug-5872.php
new file mode 100644
index 0000000000..ff16caea99
--- /dev/null
+++ b/tests/PHPStan/Rules/Functions/data/bug-5872.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace Bug5872;
+
+class HelloWorld
+{
+	/**
+	 * @phpstan-param mixed[] $mixedArray
+	 */
+	public function sayHello(array $mixedArray): void
+	{
+		var_dump(array_map('\strval', $mixedArray["api"]));
+		var_dump(array_map('\strval', (array) $mixedArray["api"]));
+	}
+}