diff --git a/NEWS b/NEWS
index eda4a46ed23..0e6efd76cd1 100644
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,8 @@ PHP                                                                        NEWS
     property). (Nikita)
   . Fixed bug #78441 (Parse error due to heredoc identifier followed by digit).
     (cmb)
+  . Fixed bug #77812 (Interactive mode does not support PHP 7.3-style heredoc).
+    (cmb, Nikita)
 
 - Intl:
   . Ensure IDNA2003 rules are used with idn_to_ascii() and idn_to_utf8()
diff --git a/ext/readline/readline_cli.c b/ext/readline/readline_cli.c
index 69ebe117cb1..6e6e9161be4 100644
--- a/ext/readline/readline_cli.c
+++ b/ext/readline/readline_cli.c
@@ -347,11 +347,14 @@ static int cli_is_valid_code(char *code, size_t len, zend_string **prompt) /* {{
 				}
 				break;
 			case heredoc:
-				if (code[i - (heredoc_len + 1)] == '\n' && !strncmp(code + i - heredoc_len, heredoc_tag, heredoc_len) && code[i] == '\n') {
+				if (!strncmp(code + i - heredoc_len + 1, heredoc_tag, heredoc_len)) {
+					unsigned char c = code[i + 1];
+					char *p = code + i - heredoc_len;
+
+					if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') || c == '_' || c >= 0x80) break;
+					while (*p == ' ' || *p == '\t') p--;
+					if (*p != '\n') break;
 					code_type = body;
-				} else if (code[i - (heredoc_len + 2)] == '\n' && !strncmp(code + i - heredoc_len - 1, heredoc_tag, heredoc_len) && code[i-1] == ';' && code[i] == '\n') {
-					code_type = body;
-					valid_end = 1;
 				}
 				break;
 			case outside:
diff --git a/ext/readline/tests/bug77812-libedit.phpt b/ext/readline/tests/bug77812-libedit.phpt
new file mode 100644
index 00000000000..478274a19a4
--- /dev/null
+++ b/ext/readline/tests/bug77812-libedit.phpt
@@ -0,0 +1,34 @@
+--TEST--
+Bug #77812 (Interactive mode does not support PHP 7.3-style heredoc)
+--SKIPIF--
+<?php
+if (!extension_loaded('readline')) die('skip readline extension not available');
+if (READLINE_LIB !== "libedit") die('skip libedit only');
+if (!function_exists('proc_open')) die('skip proc_open() not available');
+?>
+--FILE--
+<?php
+$php = getenv('TEST_PHP_EXECUTABLE');
+$ini = getenv('TEST_PHP_EXTRA_ARGS');
+$descriptorspec = [['pipe', 'r'], STDOUT, STDERR];
+$proc = proc_open("$php $ini -a", $descriptorspec, $pipes);
+var_dump($proc);
+fwrite($pipes[0], "echo <<<FOO\n    bar\n    FOO;\n");
+fwrite($pipes[0], "print(<<<FOO\nxx\nFOO);\n");
+fwrite($pipes[0], "echo <<<FOO\n    xxx\n    FOO;\nFOO\n;\n");
+fwrite($pipes[0], "echo <<<FOO\nFOOL\nFOO\n,1;\n");
+fwrite($pipes[0], "echo <<<FOO\nFOO4\nFOO\n,2;\n");
+fclose($pipes[0]);
+proc_close($proc);
+?>
+--EXPECTF--
+resource(%d) of type (process)
+Interactive shell
+
+bar
+xx
+xxx
+
+Warning: Use of undefined constant FOO - assumed 'FOO' (this will throw an Error in a future version of PHP) in php shell code on line %d
+FOOL1
+FOO42
diff --git a/ext/readline/tests/bug77812-readline.phpt b/ext/readline/tests/bug77812-readline.phpt
new file mode 100644
index 00000000000..32d9f4d9604
--- /dev/null
+++ b/ext/readline/tests/bug77812-readline.phpt
@@ -0,0 +1,54 @@
+--TEST--
+Bug #77812 (Interactive mode does not support PHP 7.3-style heredoc)
+--SKIPIF--
+<?php
+if (!extension_loaded('readline')) die('skip readline extension not available');
+if (READLINE_LIB !== "readline") die('skip readline only');
+if (!function_exists('proc_open')) die('skip proc_open() not available');
+?>
+--FILE--
+<?php
+$php = getenv('TEST_PHP_EXECUTABLE');
+$ini = getenv('TEST_PHP_EXTRA_ARGS');
+$descriptorspec = [['pipe', 'r'], STDOUT, STDERR];
+$proc = proc_open("$php $ini -a", $descriptorspec, $pipes);
+var_dump($proc);
+fwrite($pipes[0], "echo <<<FOO\n    bar\n    FOO;\n");
+fwrite($pipes[0], "print(<<<FOO\nxx\nFOO);\n");
+fwrite($pipes[0], "echo <<<FOO\n    xxx\n    FOO;\nFOO\n;\n");
+fwrite($pipes[0], "echo <<<FOO\nFOOL\nFOO\n,1;\n");
+fwrite($pipes[0], "echo <<<FOO\nFOO4\nFOO\n,2;\n");
+fclose($pipes[0]);
+proc_close($proc);
+?>
+--EXPECTF--
+resource(%d) of type (process)
+Interactive shell
+
+php > echo <<<FOO
+<<< >     bar
+<<< >     FOO;
+bar
+php > print(<<<FOO
+<<< > xx
+<<< > FOO);
+xx
+php > echo <<<FOO
+<<< >     xxx
+<<< >     FOO;
+xxx
+php > FOO
+php > ;
+
+Warning: Use of undefined constant FOO - assumed 'FOO' (this will throw an Error in a future version of PHP) in php shell code on line %d
+php > echo <<<FOO
+<<< > FOOL
+<<< > FOO
+php > ,1;
+FOOL1
+php > echo <<<FOO
+<<< > FOO4
+<<< > FOO
+php > ,2;
+FOO42
+php >