diff --git a/ext/openssl/openssl.c b/ext/openssl/openssl.c
index 2f9e160b57e58..ff4abea39d50b 100644
--- a/ext/openssl/openssl.c
+++ b/ext/openssl/openssl.c
@@ -2356,6 +2356,14 @@ PHP_FUNCTION(openssl_pkey_derive)
 		RETURN_THROWS();
 	}
 
+	if (ZEND_NUM_ARGS() == 3) {
+		php_error_docref(NULL, E_DEPRECATED,
+			"the $key_length parameter is deprecated as it is either ignored or truncates the key");
+		if (UNEXPECTED(EG(exception))) {
+			RETURN_THROWS();
+		}
+	}
+
 	if (key_len < 0) {
 		zend_argument_value_error(3, "must be greater than or equal to 0");
 		RETURN_THROWS();
diff --git a/ext/openssl/tests/gh19428.phpt b/ext/openssl/tests/gh19428.phpt
index 5d290f32e62a5..373b49b525319 100644
--- a/ext/openssl/tests/gh19428.phpt
+++ b/ext/openssl/tests/gh19428.phpt
@@ -40,5 +40,6 @@ dtlkbGbtoDOnxeNnN93gwQZngGYZYciu
 var_dump(openssl_pkey_derive($pub, $priv, 10));
 
 ?>
---EXPECT--
+--EXPECTF--
+Deprecated: openssl_pkey_derive(): the $key_length parameter is deprecated as it is either ignored or truncates the key in %s on line %d
 bool(false)
diff --git a/ext/openssl/tests/openssl_pkey_derive_deprecated_key_length_param.phpt b/ext/openssl/tests/openssl_pkey_derive_deprecated_key_length_param.phpt
new file mode 100644
index 0000000000000..b6a4c91675359
--- /dev/null
+++ b/ext/openssl/tests/openssl_pkey_derive_deprecated_key_length_param.phpt
@@ -0,0 +1,45 @@
+--TEST--
+openssl_pkey_derive() DH
+--EXTENSIONS--
+openssl
+--FILE--
+<?php
+
+$priv = openssl_pkey_get_private("-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----
+");
+
+$pub = openssl_pkey_get_public("-----BEGIN PUBLIC KEY-----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+-----END PUBLIC KEY-----
+");
+
+var_dump(bin2hex(openssl_pkey_derive($pub, $priv, 1000)));
+
+?>
+--EXPECTF--
+Deprecated: openssl_pkey_derive(): the $key_length parameter is deprecated as it is either ignored or truncates the key in %s on line %d
+string(512) "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"