diff --git a/project/config/cfgdefs.sh b/project/config/cfgdefs.sh
index 55af928..b0e7270 100644
--- a/project/config/cfgdefs.sh
+++ b/project/config/cfgdefs.sh
@@ -217,6 +217,7 @@ cfgdefs_perform_common_tests()
 
 	mb_cfgtest_headers='pthread.h'
 	cfgtest_type_size 'pthread_t'
+	cfgtest_type_size 'pthread_key_t'
 
 	# toolchain
 	cfgtest_newline