Index: ext/date/date_core.c
===================================================================
--- ext/date/date_core.c	(revision 53395)
+++ ext/date/date_core.c	(working copy)
@@ -3398,15 +3398,31 @@
     fr2 = INT2FIX(0);
     sg = DEFAULT_SG;
 
+
     switch (argc) {
       case 4:
-	val2sg(vsg, sg);
+        val2sg(vsg, sg);
       case 3:
-	num2int_with_frac(d, positive_inf);
+        if (!(TYPE(vd) == T_FLOAT || 
+              TYPE(vd) == T_FIXNUM || 
+              TYPE(vd) == T_BIGNUM)) { 
+          rb_raise(rb_eArgError, "invalid day"); 
+        }
+        num2int_with_frac(d, positive_inf);
       case 2:
-	m = NUM2INT(vm);
+        if (!(TYPE(vm) == T_FLOAT || 
+              TYPE(vm) == T_FIXNUM || 
+              TYPE(vm) == T_BIGNUM)) { 
+          rb_raise(rb_eArgError, "invalid month"); 
+        }
+        m = NUM2INT(vm);
       case 1:
-	y = vy;
+        if (!(TYPE(vy) == T_FLOAT || 
+              TYPE(vy) == T_FIXNUM || 
+              TYPE(vy) == T_BIGNUM)) { 
+          rb_raise(rb_eArgError, "invalid year"); 
+        }
+        y = vy;
     }
 
     if (guess_style(y, sg) < 0) {