diff --git a/src/org/jruby/RubyRegexp.java b/src/org/jruby/RubyRegexp.java
index e9e04691434..16ac07a2540 100644
--- a/src/org/jruby/RubyRegexp.java
+++ b/src/org/jruby/RubyRegexp.java
@@ -396,7 +396,7 @@ private Encoding checkEncoding(RubyString str, boolean warn) {
         return enc;
     }
 
-    final Regex preparePattern(RubyString str) {
+    public final Regex preparePattern(RubyString str) {
         check();
         Encoding enc = checkEncoding(str, true);
         if (enc == pattern.getEncoding()) return pattern;
diff --git a/src/org/jruby/ext/strscan/RubyStringScanner.java b/src/org/jruby/ext/strscan/RubyStringScanner.java
index 822a59b6265..4eee7ad6b00 100644
--- a/src/org/jruby/ext/strscan/RubyStringScanner.java
+++ b/src/org/jruby/ext/strscan/RubyStringScanner.java
@@ -227,10 +227,11 @@ private IRubyObject extractBegLen(Ruby runtime, int beg, int len) {
     }
     
     private IRubyObject scan(IRubyObject regex, boolean succptr, boolean getstr, boolean headonly) {
-        if (!(regex instanceof RubyRegexp)) throw getRuntime().newTypeError("wrong argument type " + regex.getMetaClass() + " (expected Regexp)");
+        Ruby runtime = getRuntime();
+        if (!(regex instanceof RubyRegexp)) throw runtime.newTypeError("wrong argument type " + regex.getMetaClass() + " (expected Regexp)");
         check();
         
-        Regex pattern = ((RubyRegexp)regex).getPattern();
+        Regex pattern = ((RubyRegexp)regex).preparePattern(str);
 
         clearMatched();
         int rest = str.getByteList().getRealSize() - pos;