diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 42a766a9d98..deb1321957e 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,10 @@
+2001-11-21  Paolo Carlini  <pcarlini@unitus.it>
+
+	PR libstdc++/4548
+	* include/bits/basic_string.tcc (basic_string::reserve):  Never shrink
+	below the current size.
+	* testsuite/21_strings/capacity.cc (test02):  Add test.
+
 2001-11-19  Phil Edwards  <pme@gcc.gnu.org>
 
 	* docs/doxygen/Intro.3:  More notes.
diff --git a/libstdc++-v3/include/bits/basic_string.tcc b/libstdc++-v3/include/bits/basic_string.tcc
index 84ec0cfc132..d1dd1cb5d99 100644
--- a/libstdc++-v3/include/bits/basic_string.tcc
+++ b/libstdc++-v3/include/bits/basic_string.tcc
@@ -315,6 +315,9 @@ namespace std
         {
 	  if (__res > this->max_size())
 	    __throw_length_error("basic_string::reserve");
+	  // Make sure we don't shrink below the current size
+	  if (__res < this->size())
+	    __res = this->size();
 	  allocator_type __a = get_allocator();
 	  _CharT* __tmp = _M_rep()->_M_clone(__a, __res - this->size());
 	  _M_rep()->_M_dispose(__a);
diff --git a/libstdc++-v3/testsuite/21_strings/capacity.cc b/libstdc++-v3/testsuite/21_strings/capacity.cc
index ed47e4e26f2..8239f1b6488 100644
--- a/libstdc++-v3/testsuite/21_strings/capacity.cc
+++ b/libstdc++-v3/testsuite/21_strings/capacity.cc
@@ -169,9 +169,30 @@ bool test01()
   return test;
 }
 
+// libstdc++/4548
+// http://gcc.gnu.org/ml/libstdc++/2001-11/msg00150.html
+bool test02()
+{
+  bool test = true;
+
+  std::string str01 = "twelve chars";
+  // str01 becomes shared
+  std::string str02 = str01;
+  str01.reserve(1);
+  VERIFY( str01.capacity() == 12 );
+
+#ifdef DEBUG_ASSERT
+  assert(test);
+#endif
+
+  return test;
+}
+
+
 int main()
 {
   test01();
+  test02();
 
   return 0;
 }