diff --git a/ChangeLog b/ChangeLog
index 87e48a48e3..612f2f7e78 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Thu Sep  4 23:47:05 2008  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* ext/bigdecimal/bigdecimal.c (BigDecimal_mode): set exception mode
+	  correctly.  In spite of BigDecimal.mode(BigDecimal::EXCEPTION_ALL,
+	  true), BigDecimal.new("NaN") did not raise an exception previously.
+
 Thu Sep  4 23:42:42 2008  Tanaka Akira  <akr@fsij.org>
 
 	* include/ruby/intern.h (rb_file_open_str): declared.
diff --git a/ext/bigdecimal/bigdecimal.c b/ext/bigdecimal/bigdecimal.c
index e8da7cc415..754c319991 100644
--- a/ext/bigdecimal/bigdecimal.c
+++ b/ext/bigdecimal/bigdecimal.c
@@ -412,11 +412,17 @@ BigDecimal_mode(int argc, VALUE *argv, VALUE self)
             VpSetException((unsigned short)((val==Qtrue)?(fo|VP_EXCEPTION_INFINITY):
                            (fo&(~VP_EXCEPTION_INFINITY))));
         }
+        fo = VpGetException();
         if(f&VP_EXCEPTION_NaN) {
             VpSetException((unsigned short)((val==Qtrue)?(fo|VP_EXCEPTION_NaN):
                            (fo&(~VP_EXCEPTION_NaN))));
         }
         fo = VpGetException();
+        if(f&VP_EXCEPTION_UNDERFLOW) {
+            VpSetException((unsigned short)((val==Qtrue)?(fo|VP_EXCEPTION_UNDERFLOW):
+                           (fo&(~VP_EXCEPTION_UNDERFLOW))));
+        }
+        fo = VpGetException();
         return INT2FIX(fo);
     }
     if(VP_ROUND_MODE==f) {