diff --git a/extern/libcds/cds/opt/options.h b/extern/libcds/cds/opt/options.h
index fc1509bc621..574c3e07a86 100644
--- a/extern/libcds/cds/opt/options.h
+++ b/extern/libcds/cds/opt/options.h
@@ -342,7 +342,7 @@ namespace opt {
     //@endcond
 
     /// Special padding constants for \p cds::opt::padding option
-    enum special_padding {
+    enum special_padding : unsigned int {
         no_special_padding = 0,   ///< no special padding
         cache_line_padding = 1,   ///< use cache line size defined in cds/user_setup/cache_line.h