diff --git a/wgrib2/CMakeLists.txt b/wgrib2/CMakeLists.txt
index 878fe63..9e1d006 100644
--- a/wgrib2/CMakeLists.txt
+++ b/wgrib2/CMakeLists.txt
@@ -153,7 +153,7 @@ target_link_libraries(wgrib2_exe PRIVATE obj_lib)
 
 if(BUILD_LIB)
   set(headers wgrib2_api.h wgrib2.h ${CMAKE_BINARY_DIR}/wgrib2/wgrib2_meta.h)
-##   target_link_libraries(wgrib2_lib PUBLIC gctpc)
+  target_link_libraries(wgrib2_lib PUBLIC gctpc -lm)
   set_target_properties(wgrib2_lib PROPERTIES PUBLIC_HEADER "${headers}")
   target_compile_definitions(wgrib2_lib PUBLIC ${definitions_list})