diff --git a/.travis.yml b/.travis.yml
index a0c465f..eff3af6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -137,6 +137,12 @@ script:
   - ${CC} -Wall -Wextra -Werror --std=gnu89 -DFT_CONGIG_HAVE_WCHAR fort.c -c -o fort.o 
   - rm fort.o 
   - cd .. 
+
+  # basic build c++ compiler
+  - cd lib 
+  - ${CXX} -Wall -Wextra -Werror fort.c -c -o fort.o 
+  - rm fort.o 
+  - cd .. 
  
 
   # cppcheck run
diff --git a/lib/fort.c b/lib/fort.c
index 9b1bd68..e470ce3 100644
--- a/lib/fort.c
+++ b/lib/fort.c
@@ -2927,14 +2927,14 @@ static fort_status_t set_cell_property_impl(fort_cell_props_t *opt, uint32_t pro
         if (v == FT_TSTYLE_DEFAULT) {
             opt->cell_text_style = FT_TSTYLE_DEFAULT;
         } else {
-            opt->cell_text_style |= v;
+            opt->cell_text_style = (enum ft_text_style)(opt->cell_text_style | v);
         }
     } else if (PROP_IS_SET(property, FT_CPROP_CONT_TEXT_STYLE)) {
         enum ft_text_style v = (enum ft_text_style)value;
         if (v == FT_TSTYLE_DEFAULT) {
             opt->content_text_style = v;
         } else {
-            opt->content_text_style |= v;
+            opt->content_text_style = (enum ft_text_style)(opt->content_text_style | v);
         }
     }
 
diff --git a/src/properties.c b/src/properties.c
index 67a2f41..a193355 100644
--- a/src/properties.c
+++ b/src/properties.c
@@ -471,14 +471,14 @@ static fort_status_t set_cell_property_impl(fort_cell_props_t *opt, uint32_t pro
         if (v == FT_TSTYLE_DEFAULT) {
             opt->cell_text_style = FT_TSTYLE_DEFAULT;
         } else {
-            opt->cell_text_style |= v;
+            opt->cell_text_style = (enum ft_text_style)(opt->cell_text_style | v);
         }
     } else if (PROP_IS_SET(property, FT_CPROP_CONT_TEXT_STYLE)) {
         enum ft_text_style v = (enum ft_text_style)value;
         if (v == FT_TSTYLE_DEFAULT) {
             opt->content_text_style = v;
         } else {
-            opt->content_text_style |= v;
+            opt->content_text_style = (enum ft_text_style)(opt->content_text_style | v);
         }
     }