diff --git a/src/Validation/Rules/Library/RuleString.php b/src/Validation/Rules/Library/RuleString.php
index 376b9a8..2505808 100644
--- a/src/Validation/Rules/Library/RuleString.php
+++ b/src/Validation/Rules/Library/RuleString.php
@@ -98,9 +98,13 @@ public function min(int $len): void
 
     public function regexp(string $expr): void
     {
-        if (!preg_match(sprintf("#%s#", $expr), $this->value)) {
-            throw new RuleFailed(sprintf("string does not match regular expression %s", $expr));
-        }
+      if(@preg_match($expr, '') === FALSE) {
+        throw new RuleFailed(sprintf("regexp is not a valid regular expression %s", $expr));
+      }
+
+      if(!preg_match($expr, $this->value)) {
+        throw new RuleFailed(sprintf("string does not match regular expression %s", $expr));
+      }
     }
 
     public function url(): void
@@ -113,4 +117,4 @@ public function between(int $min, int $max): void
         $this->min($min);
         $this->max($max);
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Parsing/Simple/SimpleRuleParserTest.php b/tests/Parsing/Simple/SimpleRuleParserTest.php
index 0059b1a..202e01e 100644
--- a/tests/Parsing/Simple/SimpleRuleParserTest.php
+++ b/tests/Parsing/Simple/SimpleRuleParserTest.php
@@ -54,8 +54,8 @@ public function goodTestSet(): array
             [":string ?", [TokenRule::make("string", []), TokenQuantifier::make(0, 1)]],
             [":string('\'')", [TokenRule::make("string", ["'"])]],
             [
-                ":string :regexp('\w{1,4}') {1}",
-                [TokenRule::make("string", []), TokenSubRule::make("regexp", ['\w{1,4}']), TokenQuantifier::make(1, 1)],
+                ":string :regexp('/\w{1,4}/') {1}",
+                [TokenRule::make("string", []), TokenSubRule::make("regexp", ['/\w{1,4}/']), TokenQuantifier::make(1, 1)],
             ],
             [":string :min(501)", [TokenRule::make("string", []), TokenSubRule::make("min", [501])]],
             [":string? :min(1)", [TokenNullableRule::make("string", []), TokenSubRule::make("min", [1])]],
diff --git a/tests/Validation/ArrayValidatorTest.php b/tests/Validation/ArrayValidatorTest.php
index b3e0ef8..21b65ed 100644
--- a/tests/Validation/ArrayValidatorTest.php
+++ b/tests/Validation/ArrayValidatorTest.php
@@ -20,7 +20,7 @@ public function data(): array
             [[], [':exact("name")?' => ':string'], self::EXPECT_PASS],
             [['name' => 'John Dutton'], ['name' => ':string'], self::EXPECT_PASS],
             [['name' => 'Kayce Dutton'], ['name' => ':string :min(20)'], self::EXPECT_FAIL],
-            [['name' => 'Kayce Dutton'], ['name' => ':string :regexp("Jamie")'], self::EXPECT_FAIL],
+            [['name' => 'Kayce Dutton'], ['name' => ':string :regexp("/Jamie/")'], self::EXPECT_FAIL],
             [['name' => 'Jamie', 'lastname' => 'Dutton'], [':string {2}' => ':string'], self::EXPECT_PASS],
             [['name' => 'Beth Dutton'], ['*' => ':string or :number'], self::EXPECT_PASS],
             [['12' => ''], [':string' => ''], self::EXPECT_FAIL],
@@ -52,14 +52,14 @@ public function data(): array
                     "lastname" => "",
                 ],
                 [
-                    ":string :regexp('\w{0,4}') {1}" => ":any",
-                    ":string :regexp('\w{0,}') {1}" => ":any",
+                    ":string :regexp('/\w{0,4}/') {1}" => ":any",
+                    ":string :regexp('/\w{0,}/') {1}" => ":any",
                 ],
                 self::EXPECT_PASS,
             ],
             [
                 ["name" => "John"],
-                [':string :regexp("\w{1,4}") {1}' => ":any"],
+                [':string :regexp("/\w{1,4}/") {1}' => ":any"],
                 self::EXPECT_PASS,
             ],
             [
@@ -156,7 +156,7 @@ public function data(): array
                     "last_name" => "Walberg",
                 ],
                 [
-                    ":string :regexp('(first|last)_name') *" => ":string",
+                    ":string :regexp('/(first|last)_name/') *" => ":string",
                 ],
                 self::EXPECT_PASS,
             ],
diff --git a/tests/Validation/Rules/Library/RuleStringTest.php b/tests/Validation/Rules/Library/RuleStringTest.php
index 7c1b8c9..5dfb08b 100644
--- a/tests/Validation/Rules/Library/RuleStringTest.php
+++ b/tests/Validation/Rules/Library/RuleStringTest.php
@@ -32,8 +32,12 @@ public function data(): array
             ['max', [3], 'abcd', self::SHOULD_FAIL],
             ['between', [1, 3], 'abc', self::SHOULD_SUCCEED],
             ['between', [1, 3], 'abcd', self::SHOULD_FAIL],
-            ['regexp', ['^[a]+$'], 'aa', self::SHOULD_SUCCEED],
-            ['regexp', ['^[a]+$'], 'ab', self::SHOULD_FAIL],
+            ['regexp', ['/^[a]+$/'], 'aa', self::SHOULD_SUCCEED],
+            ['regexp', ['/^[a]+$/'], 'ab', self::SHOULD_FAIL],
+            ['regexp', ['^[a]+$'], 'aa', self::SHOULD_FAIL],
+            ['regexp', ['#^[a]+$#'], 'aa', self::SHOULD_SUCCEED],
+            ['regexp', ['@^[a]+$@'], 'aa', self::SHOULD_SUCCEED],
+            ['regexp', ['/^(https?:\/\/)/i'], 'http://github.com', self::SHOULD_SUCCEED],
             ['contains', ['bb'], 'abba', self::SHOULD_SUCCEED],
             ['contains', ['bb'], 'ab', self::SHOULD_FAIL],
             ['starts', ['na'], 'name', self::SHOULD_SUCCEED],