Fix typo in CMakeLists.txt
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index ebcfea9..182e3a6 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -131,7 +131,7 @@
     set(libs ${libs} pthread)
 endif()
 
-set(lib ${libs} tinycrypt)
+set(libs ${libs} tinycrypt)
 
 if (NOT USE_STATIC_MBEDTLS_LIBRARY AND NOT USE_SHARED_MBEDTLS_LIBRARY)
     message(FATAL_ERROR "Need to choose static or shared mbedtls build!")