diff --git a/include/boost/unordered/detail/foa.hpp b/include/boost/unordered/detail/foa.hpp
index 614654a3..37de4346 100644
--- a/include/boost/unordered/detail/foa.hpp
+++ b/include/boost/unordered/detail/foa.hpp
@@ -1367,6 +1367,24 @@ private:
 #endif
   }
 
+/* GCC and clang (including clang-win toolsets) will generate warnings when the
+ * KeyEqual predicate returns an integral type such as std::size_t because the
+ * implementation of __builtin_expect() accepts long as its argument types.
+ * 
+ * Because we can't control this, it's easiest to simply silence the warning
+ * instead of introducing any potential performance pitfalls.
+ */
+#if defined(BOOST_GCC)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wsign-conversion"
+#endif
+
+#if defined(BOOST_CLANG)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wshorten-64-to-32"
+#pragma clang diagnostic ignored "-Wsign-conversion"
+#endif
+
   template<typename Key>
   BOOST_FORCEINLINE iterator find_impl(
     const Key& x,std::size_t pos0,std::size_t hash)const
@@ -1381,7 +1399,7 @@ private:
         prefetch_elements(p);
         do{
           auto n=unchecked_countr_zero(mask);
-          if(BOOST_LIKELY(static_cast<bool>(pred()(x,key_from(p[n]))))){
+          if(BOOST_LIKELY(pred()(x,key_from(p[n])))){
             return {pg,n,p+n};
           }
           mask&=mask-1;
@@ -1394,6 +1412,13 @@ private:
     while(BOOST_LIKELY(pb.next(arrays.groups_size_mask)));
     return {}; // TODO end() does not work (returns const_iterator)
   }
+#if defined(BOOST_CLANG)
+#pragma clang diagnostic pop /* ignored "-Wshorten-64-to-32", "-Wsign-conversion" */
+#endif
+
+#if defined(BOOST_GCC)
+#pragma GCC diagnostic pop /* ignored "-Wsign-conversion" */
+#endif
 
   template<typename... Args>
   BOOST_FORCEINLINE std::pair<iterator,bool> emplace_impl(Args&&... args)