Index: src/tests/CMakeLists.txt
--- src/tests/CMakeLists.txt.orig
+++ src/tests/CMakeLists.txt
@@ -1,7 +1,7 @@
 # Build PROJ test programs and run tests (only invoked if BUILD_TESTING)
 
 add_executable(geodtest geodtest.c)
-target_link_libraries(geodtest ${PROJ_LIBRARIES})
+target_link_libraries(geodtest m ${PROJ_LIBRARIES})
 
 add_executable(geodsigntest geodsigntest.c)
 # geodsigntest includes geodesic.c directly so it doesn't need to link
