diff --git a/lib/liquid/expression.rb b/lib/liquid/expression.rb
index 9a48952a..981946ef 100644
--- a/lib/liquid/expression.rb
+++ b/lib/liquid/expression.rb
@@ -78,61 +78,74 @@ module Liquid
         end
       end
 
-      def parse_number(markup, ss)
+      def parse_number(markup, _ss = nil)
+        len = markup.bytesize
+        return false if len == 0
+
         # Quick reject: first byte must be digit or dash
-        first = markup.getbyte(0)
-        return false if first != DASH && (first < ZERO || first > NINE)
+        pos = 0
+        first = markup.getbyte(pos)
+        if first == DASH
+          pos += 1
+          return false if pos >= len
+          b = markup.getbyte(pos)
+          return false if b < ZERO || b > NINE
+          pos += 1
+        elsif first >= ZERO && first <= NINE
+          pos += 1
+        else
+          return false
+        end
 
-        # check if the markup is simple integer or float
-        case markup
-        when INTEGER_REGEX
+        # Scan digits
+        while pos < len
+          b = markup.getbyte(pos)
+          break unless b >= ZERO && b <= NINE
+          pos += 1
+        end
+
+        # If we consumed everything, it's a simple integer
+        if pos == len
           return Integer(markup, 10)
-        when FLOAT_REGEX
-          return markup.to_f
         end
 
-        ss.string = markup
-        # the first byte must be a digit or  a dash
-        byte = ss.scan_byte
+        # Check for dot (float)
+        if markup.getbyte(pos) == DOT
+          dot_pos = pos
+          pos += 1
+          # Must have at least one digit after dot
+          digit_after_dot = pos
+          while pos < len
+            b = markup.getbyte(pos)
+            break unless b >= ZERO && b <= NINE
+            pos += 1
+          end
 
-        return false if byte != DASH && (byte < ZERO || byte > NINE)
-
-        if byte == DASH
-          peek_byte = ss.peek_byte
-
-          # if it starts with a dash, the next byte must be a digit
-          return false if peek_byte.nil? || !(peek_byte >= ZERO && peek_byte <= NINE)
-        end
-
-        # The markup could be a float with multiple dots
-        first_dot_pos = nil
-        num_end_pos = nil
-
-        while (byte = ss.scan_byte)
-          return false if byte != DOT && (byte < ZERO || byte > NINE)
-
-          # we found our number and now we are just scanning the rest of the string
-          next if num_end_pos
-
-          if byte == DOT
-            if first_dot_pos.nil?
-              first_dot_pos = ss.pos
-            else
-              # we found another dot, so we know that the number ends here
-              num_end_pos = ss.pos - 1
+          if pos > digit_after_dot && pos == len
+            # Simple float like "123.456"
+            return markup.to_f
+          elsif pos > digit_after_dot
+            # Float followed by more dots or other chars: "1.2.3.4"
+            # Return the float portion up to second dot
+            first_dot_pos = dot_pos + 1
+            while pos < len
+              b = markup.getbyte(pos)
+              if b == DOT
+                return markup.byteslice(0, pos).to_f
+              elsif b < ZERO || b > NINE
+                return false
+              end
+              pos += 1
             end
+            return markup.byteslice(0, pos).to_f
+          else
+            # dot at end: "123."
+            return markup.byteslice(0, dot_pos).to_f
           end
         end
 
-        num_end_pos = markup.length if ss.eos?
-
-        if num_end_pos
-          # number ends with a number "123.123"
-          markup.byteslice(0, num_end_pos).to_f
-        else
-          # number ends with a dot "123."
-          markup.byteslice(0, first_dot_pos).to_f
-        end
+        # Not a number (has non-digit, non-dot characters)
+        false
       end
     end
   end