diff --git a/ext/jruby/org/jruby/ext/strscan/RubyStringScanner.java b/ext/jruby/org/jruby/ext/strscan/RubyStringScanner.java
index a1e81effcd..7d3e7494fc 100644
--- a/ext/jruby/org/jruby/ext/strscan/RubyStringScanner.java
+++ b/ext/jruby/org/jruby/ext/strscan/RubyStringScanner.java
@@ -265,7 +265,8 @@ private IRubyObject scan(ThreadContext context, IRubyObject regex, boolean succp
         check(context);
         clearMatched();
 
-        if (restLen() < 0) {
+        int restLen = restLen();
+        if (restLen < 0) {
             return context.nil;
         }
 
@@ -275,7 +276,7 @@ private IRubyObject scan(ThreadContext context, IRubyObject regex, boolean succp
         if (regex instanceof RubyRegexp) {
             pattern = ((RubyRegexp) regex).preparePattern(str);
 
-            int range = currPtr + restLen();
+            int range = currPtr + restLen;
 
             Matcher matcher = pattern.matcher(strBL.getUnsafeBytes(), matchTarget(), range);
             final int ret;
@@ -298,17 +299,14 @@ private IRubyObject scan(ThreadContext context, IRubyObject regex, boolean succp
             if (ret < 0) return context.nil;
         } else {
             RubyString pattern = regex.convertToString();
-
             Encoding patternEnc = str.checkEncoding(pattern);
-
-            if (restLen() < pattern.size()) {
-                return context.nil;
-            }
-
             ByteList patternBL = pattern.getByteList();
             int patternSize = patternBL.realSize();
 
             if (headonly) {
+                if (restLen < pattern.size()) {
+                    return context.nil;
+                }
                 if (ByteList.memcmp(strBL.unsafeBytes(), currPtr, patternBL.unsafeBytes(), patternBL.begin(), patternSize) != 0) {
                     return context.nil;
                 }
diff --git a/test/strscan/test_stringscanner.rb b/test/strscan/test_stringscanner.rb
index 9b7b7910d0..54fd5027cf 100644
--- a/test/strscan/test_stringscanner.rb
+++ b/test/strscan/test_stringscanner.rb
@@ -325,6 +325,9 @@ def test_scan_string
     s = create_string_scanner(str, false)
     matched = s.scan('str')
     assert_equal 'str', matched
+
+    s = create_string_scanner("str")
+    assert_equal nil, s.scan("str\0\0")
   end
 
   def test_skip
@@ -710,6 +713,9 @@ def test_scan_until_string
     assert_equal(nil, s.skip_until("Qux"))
     assert_equal("\u0000Baz", s.scan_until("Baz"))
     assert_equal(11, s.pos)
+
+    s = create_string_scanner("str")
+    assert_equal nil, s.scan_until("str\0\0")
   end
 
   def test_skip_until