diff --git a/Sources/StencilSwiftKit/Environment.swift b/Sources/StencilSwiftKit/Environment.swift
index d73127ee..52312743 100644
--- a/Sources/StencilSwiftKit/Environment.swift
+++ b/Sources/StencilSwiftKit/Environment.swift
@@ -7,7 +7,7 @@
 import Stencil
 
 public extension Extension {
-  public func registerStencilSwiftExtensions() {
+  func registerStencilSwiftExtensions() {
     registerTags()
     registerStringsFilters()
     registerNumbersFilters()
diff --git a/Sources/StencilSwiftKit/Filters+Strings.swift b/Sources/StencilSwiftKit/Filters+Strings.swift
index fde13126..afa7e7f2 100644
--- a/Sources/StencilSwiftKit/Filters+Strings.swift
+++ b/Sources/StencilSwiftKit/Filters+Strings.swift
@@ -95,7 +95,7 @@ extension Filters.Strings {
     while idx < scalars.endIndex, let scalar = UnicodeScalar(scalars[idx].value), characterSet.contains(scalar) {
       idx = scalars.index(after: idx)
     }
-    if idx > scalars.index(after: start) && idx < scalars.endIndex,
+    if !string.isEmpty && idx > scalars.index(after: start) && idx < scalars.endIndex,
       let scalar = UnicodeScalar(scalars[idx].value),
       CharacterSet.lowercaseLetters.contains(scalar) {
       idx = scalars.index(before: idx)
@@ -264,9 +264,22 @@ extension Filters.Strings {
     let source = try Filters.parseString(from: value)
     let substring = try Filters.parseStringArgument(from: arguments, at: 0)
     let replacement = try Filters.parseStringArgument(from: arguments, at: 1)
+    if substring.first == "/" && substring.last == "/" {
+      let regex = String(substring.dropFirst().dropLast())
+      return replaceRegex(source: source, regex: regex, replacement: replacement)
+    }
     return source.replacingOccurrences(of: substring, with: replacement)
   }
 
+  /// Replaces in the given string the given regular expression with the replacement
+  /// - Parameters:
+  ///   - source: The source string
+  ///   - regex: The regular expression
+  ///   - replacement: The replacement string
+  private static func replaceRegex(source: String, regex: String, replacement: String) -> String {
+    return source.replacingOccurrences(of: regex, with: replacement, options: .regularExpression)
+  }
+
   /// Converts an arbitrary string to a valid swift identifier. Takes an optional Mode argument:
   ///   - normal (default): uppercase the first character, prefix with an underscore if starting
   ///     with a number, replace invalid characters by underscores
diff --git a/Tests/StencilSwiftKitTests/StringFiltersTests.swift b/Tests/StencilSwiftKitTests/StringFiltersTests.swift
index 707a2a0f..5a5e80dc 100644
--- a/Tests/StencilSwiftKitTests/StringFiltersTests.swift
+++ b/Tests/StencilSwiftKitTests/StringFiltersTests.swift
@@ -470,11 +470,12 @@ extension StringFiltersTests {
 
 extension StringFiltersTests {
   func testReplace() throws {
-    let expectations = [
+    let expectations: [(Input, String, String, String)] = [
       (Input(string: "string"), "ing", "oke", "stroke"),
       (Input(string: "string"), "folks", "mates", "string"),
       (Input(string: "hi mates!"), "hi", "Yo", "Yo mates!"),
-      (Input(string: "string with spaces"), " ", "_", "string_with_spaces")
+      (Input(string: "string with spaces"), " ", "_", "string_with_spaces"),
+      (Input(string: "string with numbers 42"), "/\\s\\d+$/", "", "string with numbers")
     ]
 
     for (input, substring, replacement, expected) in expectations {