diff --git a/include/boost/detail/sp_counted_base_gcc_x86.hpp b/include/boost/detail/sp_counted_base_gcc_x86.hpp
index 1792d40..235153e 100644
--- a/include/boost/detail/sp_counted_base_gcc_x86.hpp
+++ b/include/boost/detail/sp_counted_base_gcc_x86.hpp
@@ -71,7 +71,7 @@ inline long atomic_conditional_increment( long * pw )
         "cmpxchgl %%ebx, %0\n\t"
         "jne 0b\n\t"
         "1:":
-        "=m"( *pw ), "=eax"( r ): // outputs (%0, %1)
+        "=m"( *pw ), "=&eax"( r ): // outputs (%0, %1)
         "0"( *pw ): // input (%0)
         "ebx", "memory", "cc" // clobbers
     );