diff --git a/ChangeLog b/ChangeLog
index 90ecdf6311..b16c96f7ed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Feb  9 11:47:03 2008  Tanaka Akira  <akr@fsij.org>
+
+	* math.c (math_gamma): add error check.
+	  (math_lgamma): ditto.
+
 Sat Feb  9 11:09:26 2008  Tanaka Akira  <akr@fsij.org>
 
 	* missing/lgamma_r.c (lgamma_r): return HUGE_VAL for non-positive
diff --git a/math.c b/math.c
index e457716345..fd10e97008 100644
--- a/math.c
+++ b/math.c
@@ -530,8 +530,12 @@ math_erfc(VALUE obj, VALUE x)
 static VALUE
 math_gamma(VALUE obj, VALUE x)
 {
+    double d;
     Need_Float(x);
-    return DOUBLE2NUM(tgamma(RFLOAT_VALUE(x)));
+    errno = 0;
+    d = tgamma(RFLOAT_VALUE(x));
+    domain_check(d, "gamma");
+    return DOUBLE2NUM(d);
 }
 
 /*
@@ -549,10 +553,14 @@ math_gamma(VALUE obj, VALUE x)
 static VALUE
 math_lgamma(VALUE obj, VALUE x)
 {
+    double d;
     int sign;
     VALUE v;
     Need_Float(x);
-    v = DOUBLE2NUM(lgamma_r(RFLOAT_VALUE(x), &sign));
+    errno = 0;
+    d = lgamma_r(RFLOAT_VALUE(x), &sign);
+    domain_check(d, "lgamma");
+    v = DOUBLE2NUM(d);
     return rb_assoc_new(v, INT2FIX(sign));
 }