diff --git a/beast/Atomic.h b/beast/Atomic.h
index cd54d75ad0..97b271b8e3 100644
--- a/beast/Atomic.h
+++ b/beast/Atomic.h
@@ -207,6 +207,9 @@ private:
     #define BEAST_64BIT_ATOMICS_UNAVAILABLE 1
   #endif
 
+#elif BEAST_CLANG && BEAST_LINUX
+  #define BEAST_ATOMICS_GCC 1
+
 //==============================================================================
 #elif BEAST_GCC
   #define BEAST_ATOMICS_GCC 1        // GCC with intrinsics
@@ -323,7 +326,7 @@ inline Type Atomic<Type>::operator++() noexcept
     return sizeof (Type) == 4 ? (Type) beast_InterlockedIncrement ((volatile long*) &value)
                               : (Type) beast_InterlockedIncrement64 ((volatile __int64*) &value);
   #elif BEAST_ATOMICS_GCC
-    return (Type) __sync_add_and_fetch (&value, 1);
+    return (Type) __sync_add_and_fetch (&value, (Type) 1);
   #endif
 }
 
@@ -337,7 +340,7 @@ inline Type Atomic<Type>::operator--() noexcept
     return sizeof (Type) == 4 ? (Type) beast_InterlockedDecrement ((volatile long*) &value)
                               : (Type) beast_InterlockedDecrement64 ((volatile __int64*) &value);
   #elif BEAST_ATOMICS_GCC
-    return (Type) __sync_add_and_fetch (&value, -1);
+    return (Type) __sync_add_and_fetch (&value, (Type) -1);
   #endif
 }