diff --git a/completion/available/hub.completion.bash b/completion/available/hub.completion.bash
index 74c530a8..67a5e29b 100644
--- a/completion/available/hub.completion.bash
+++ b/completion/available/hub.completion.bash
@@ -23,12 +23,12 @@
 # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 # If there is no git tab completion, but we have the _completion loader try to load it
-if ! declare -F _git > /dev/null && declare -F _completion_loader > /dev/null; then
+if ! _is_function _git && _is_function _completion_loader; then
   _completion_loader git
 fi
 
 # Check that git tab completion is available and we haven't already set up completion
-if declare -F _git > /dev/null && ! declare -F __git_list_all_commands_without_hub > /dev/null; then
+if _is_function _git && ! _is_function __git_list_all_commands_without_hub; then
   # Duplicate and rename the 'list_all_commands' function
   eval "$(declare -f __git_list_all_commands | \
         sed 's/__git_list_all_commands/__git_list_all_commands_without_hub/')"