diff --git a/ChangeLog b/ChangeLog
index e4f4ecaf4f..c9c32615ff 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Mar 18 00:58:27 2010  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* util.c (ruby_strtod): Add support for Hexadecimal
+	  floating-point expression [ruby-dev:40650] #2969
+
 Thu Mar 18 00:00:58 2010  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* lib/uri/common.rb (URI#{en,de}code_www_form_component):
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index 64205f6082..5d6d6d7ab8 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -1385,6 +1385,15 @@ class TestString < Test::Unit::TestCase
     assert_equal(5.9742e24, S("5.9742e24").to_f)
     assert_equal(98.6,      S("98.6 degrees").to_f)
     assert_equal(0.0,       S("degrees 100.0").to_f)
+    assert_equal([ 0.0].pack('G'), [S(" 0.0").to_f].pack('G'))
+    assert_equal([-0.0].pack('G'), [S("-0.0").to_f].pack('G'))
+    assert_equal([ 0.0].pack('G'), [S(" 0x0p+0").to_f].pack('G'))
+    assert_equal([-0.0].pack('G'), [S("-0x0p+0").to_f].pack('G'))
+    assert_equal(1.0,       S("0X1.P+0").to_f)
+    assert_equal(1024.0,    S("0x1p+10").to_f)
+    assert_equal(0.0009765625, S("0x1p-10").to_f)
+    assert_equal(2.6881171418161356e+43, S("0x1.3494a9b171bf5p+144").to_f)
+    assert_equal(-3.720075976020836e-44, S("-0x1.a8c1f14e2af5dp-145").to_f)
   end
 
   def test_to_i
diff --git a/util.c b/util.c
index 5ebc5f3e87..9cdb563040 100644
--- a/util.c
+++ b/util.c
@@ -2106,6 +2106,44 @@ ruby_strtod(const char *s00, char **se)
         }
 break2:
     if (*s == '0') {
+	if (s[1] == 'x' || s[1] == 'X') {
+	    static const char hexdigit[] = "0123456789abcdef0123456789ABCDEF";
+	    s0 = ++s;
+	    adj = 0;
+
+	    while (*++s && (s1 = strchr(hexdigit, *s))) {
+		adj *= 16;
+		adj += (s1 - hexdigit) & 15;
+	    }
+
+	    if (*s == '.') {
+		aadj = 1.;
+		while (*++s && (s1 = strchr(hexdigit, *s))) {
+		    aadj /= 16;
+		    adj += aadj * ((s1 - hexdigit) & 15);
+		}
+	    }
+
+	    if (*s != 'P' && *s != 'p') {
+		s = s0;
+		goto ret;
+	    }
+
+	    dsign = 0x2C - *++s; /* +: 2B, -: 2D */
+	    if (abs(dsign) != 1) {
+		s = s0;
+		goto ret;
+	    }
+
+	    for (nd = 0, s++; (c = *s) >= '0' && c <= '9'; s++) {
+		nd *= 10;
+		nd += c;
+		nd -= '0';
+	    }
+
+	    dval(rv) = ldexp(adj, nd * dsign);
+	    goto ret;
+	}
         nz0 = 1;
         while (*++s == '0') ;
         if (!*s)