diff --git a/ext/standard/tests/strings/uuencode_error.phpt b/ext/standard/tests/strings/uuencode_error.phpt
new file mode 100644
index 000000000000..f58eb8752c5f
--- /dev/null
+++ b/ext/standard/tests/strings/uuencode_error.phpt
@@ -0,0 +1,40 @@
+--TEST--
+convert_uudecode() with invalid data
+--FILE--
+<?php
+$warning = null;
+set_error_handler(function (int $errno, string $errstr) use (&$warning) {
+    $warning = $errstr;
+    return true;
+});
+
+$encoded100 = convert_uuencode(str_repeat('a', 100));
+$invalid = [
+    'empty string'                         => '',
+    'length character only'                => '!',
+    'truncated group'                      => '!80',
+    'full line announced, no data'         => 'M',
+    'maximum line announced, no data'      => '_',
+    'full line announced, short data'      => 'M' . str_repeat('abcd', 5),
+    'plain text'                           => 'not uuencoded',
+    'multi-line, cut inside first line'    => substr($encoded100, 0, 30),
+    'multi-line, cut inside second line'   => substr($encoded100, 0, 92),
+    'multi-line, cut inside last line'     => substr($encoded100, 0, 132),
+];
+foreach ($invalid as $label => $input) {
+    $warning = 'no warning';
+    $result = convert_uudecode($input);
+    echo $label, ": ", var_export($result, true), ", ", $warning, "\n";
+}
+?>
+--EXPECT--
+empty string: false, convert_uudecode(): Argument #1 ($string) is not a valid uuencoded string
+length character only: false, convert_uudecode(): Argument #1 ($string) is not a valid uuencoded string
+truncated group: false, convert_uudecode(): Argument #1 ($string) is not a valid uuencoded string
+full line announced, no data: false, convert_uudecode(): Argument #1 ($string) is not a valid uuencoded string
+maximum line announced, no data: false, convert_uudecode(): Argument #1 ($string) is not a valid uuencoded string
+full line announced, short data: false, convert_uudecode(): Argument #1 ($string) is not a valid uuencoded string
+plain text: false, convert_uudecode(): Argument #1 ($string) is not a valid uuencoded string
+multi-line, cut inside first line: false, convert_uudecode(): Argument #1 ($string) is not a valid uuencoded string
+multi-line, cut inside second line: false, convert_uudecode(): Argument #1 ($string) is not a valid uuencoded string
+multi-line, cut inside last line: false, convert_uudecode(): Argument #1 ($string) is not a valid uuencoded string
diff --git a/ext/standard/tests/strings/uuencode_rt.phpt b/ext/standard/tests/strings/uuencode_rt.phpt
new file mode 100644
index 000000000000..e9354734eb85
--- /dev/null
+++ b/ext/standard/tests/strings/uuencode_rt.phpt
@@ -0,0 +1,48 @@
+--TEST--
+convert_uuencode() and convert_uudecode() round trip
+--FILE--
+<?php
+
+$vectors = [
+    'empty string' => ["", ['`']],
+    '1 byte' => ["a", ['!80``', '`']],
+    '2 bytes' => ["ab", ['"86(`', '`']],
+    '3 bytes' => ["abc", ['#86)C', '`']],
+    '4 bytes' => ["abcd", ['$86)C9```', '`']],
+    '5 bytes' => ["abcde", ['%86)C9&4`', '`']],
+    '6 bytes' => ["abcdef", ['&86)C9&5F', '`']],
+    '1 NUL' => ["\x00", ['!````', '`']],
+    '2 NULs' => ["\x00\x00", ['"````', '`']],
+    '3 NULs' => ["\x00\x00\x00", ['#````', '`']],
+    '4 NULs' => ["\x00\x00\x00\x00", ['$````````', '`']],
+    '1 x 0xFF' => ["\xff", ['!_P``', '`']],
+    '2 x 0xFF' => ["\xff\xff", ['"__\\`', '`']],
+    '3 x 0xFF' => ["\xff\xff\xff", ['#____', '`']],
+    '4 x 0xFF' => ["\xff\xff\xff\xff", ['$_____P``', '`']],
+    '5 x 0xFF' => ["\xff\xff\xff\xff\xff", ['%______\\`', '`']],
+    'manual example' => ["test\x0atext text\x0d\x0a", ['0=&5S=`IT97AT(\'1E>\'0-"@``', '`']],
+    '44 bytes' => [str_repeat('a', 44), ['L86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86$`', '`']],
+    '45 bytes (one full line)' => [str_repeat('a', 45), ['M86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A', '`']],
+    '46 bytes' => [str_repeat('a', 46), ['M86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A', '!80``', '`']],
+    '47 bytes' => [str_repeat('a', 47), ['M86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A', '"86$`', '`']],
+    '48 bytes' => [str_repeat('a', 48), ['M86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A', '#86%A', '`']],
+    '90 bytes (two full lines)' => [str_repeat('a', 90), ['M86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A', 'M86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A', '`']],
+    '93 bytes' => [str_repeat('a', 93), ['M86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A', 'M86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A86%A', '#86%A', '`']],
+];
+
+$failures = [];
+foreach ($vectors as $label => [$input, $lines]) {
+    $expected = implode("\n", $lines) . "\n";
+    if (convert_uuencode($input) !== $expected) {
+        $failures[] = "encode: $label";
+    }
+    if (convert_uudecode($expected) !== $input) {
+        $failures[] = "decode: $label";
+    }
+}
+var_dump($failures);
+
+?>
+--EXPECT--
+array(0) {
+}
\ No newline at end of file
diff --git a/ext/standard/uuencode.c b/ext/standard/uuencode.c
index 6dc2848fec0f..762fd32329b3 100644
--- a/ext/standard/uuencode.c
+++ b/ext/standard/uuencode.c
@@ -48,8 +48,6 @@
  * SUCH DAMAGE.
  */
 
-#include <math.h>
-
 #include "php.h"
 #include "php_uuencode.h"
 
@@ -80,7 +78,7 @@ PHPAPI zend_string *php_uuencode(const char *src, size_t src_len) /* {{{ */
 			ee = e;
 			len = ee - s;
 			if (len % 3) {
-				ee = s + (int) (floor((double)len / 3) * 3);
+				ee = s + (len / 3) * 3;
 			}
 		}
 		*p++ = PHP_UU_ENC(len);
@@ -135,7 +133,7 @@ PHPAPI zend_string *php_uudecode(const char *src, size_t src_len) /* {{{ */
 		return NULL;
 	}
 
-	dest = zend_string_alloc((size_t) ceil(src_len * 0.75), 0);
+	dest = zend_string_alloc(src_len - src_len / 4, 0);
 	p = ZSTR_VAL(dest);
 	s = src;
 	e = src + src_len;
@@ -151,7 +149,7 @@ PHPAPI zend_string *php_uudecode(const char *src, size_t src_len) /* {{{ */
 
 		total_len += len;
 
-		ee = s + (len == 45 ? 60 : (int) floor(len * 1.33));
+		ee = s + ((len + 2) / 3) * 4;
 		/* sanity check */
 		if (ee > e) {
 			goto err;