diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3538c64f1e9..bd038415772 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -653,10 +653,10 @@ if(UNIX AND NOT APPLE)
 		set(OPENIMAGEIO_DEFINITIONS)
 
 		if(WITH_IMAGE_TIFF)
-			set(OPENIMAGEIO_LIBRARIES "${OPENIMAGEIO_LIBRARIES} ${TIFF_LIBRARY}")
+			list(APPEND OPENIMAGEIO_LIBRARIES "${TIFF_LIBRARY}")
 		endif()
 		if(WITH_IMAGE_OPENEXR)
-			set(OPENIMAGEIO_LIBRARIES "${OPENIMAGEIO_LIBRARIES} ${OPENEXR_LIBRARIES}")
+			list(APPEND OPENIMAGEIO_LIBRARIES "${OPENEXR_LIBRARIES}")
 		endif()
 
 		if(NOT OPENIMAGEIO_FOUND)