diff --git a/src/assimp/build_vars.cmake b/src/assimp/build_vars.cmake
index 1e413fc..49d77d4 100644
--- a/src/assimp/build_vars.cmake
+++ b/src/assimp/build_vars.cmake
@@ -1,7 +1,6 @@
 # add assimp if available
-find_package(assimp 5.1 QUIET)
-if(NOT assimp_FOUND)
-find_package(assimp 5.0 QUIET)
+if (VSGXCHANGE_WITH_ASSIMP)
+find_package(assimp REQUIRED)
 endif()
 
 
diff --git a/src/curl/build_vars.cmake b/src/curl/build_vars.cmake
index 015b68c..a4afc8a 100644
--- a/src/curl/build_vars.cmake
+++ b/src/curl/build_vars.cmake
@@ -1,5 +1,7 @@
 # add CURL if available
-find_package(CURL)
+if(VSGXCHANGE_WITH_CURL)
+find_package(CURL REQUIRED)
+endif()
 
 if(CURL_FOUND)
     OPTION(vsgXchange_curl "Optional CURL support provided" ON)
diff --git a/src/freetype/build_vars.cmake b/src/freetype/build_vars.cmake
index cb63a8b..327db9e 100644
--- a/src/freetype/build_vars.cmake
+++ b/src/freetype/build_vars.cmake
@@ -1,5 +1,7 @@
 # add freetype if available
-find_package(Freetype)
+if(VSGXCHANGE_WITH_FREETYPE)
+find_package(Freetype REQUIRED)
+endif()
 
 if(FREETYPE_FOUND)
     OPTION(vsgXchange_freetype "Freetype support provided" ON)
diff --git a/src/gdal/build_vars.cmake b/src/gdal/build_vars.cmake
index dd240b0..227c6b7 100644
--- a/src/gdal/build_vars.cmake
+++ b/src/gdal/build_vars.cmake
@@ -1,5 +1,7 @@
 # add GDAL if available
-find_package(GDAL QUIET)
+if(VSGXCHANGE_WITH_GDAL)
+find_package(GDAL REQUIRED)
+endif()
 
 if(GDAL_FOUND)
     OPTION(vsgXchange_GDAL "GDAL support provided" ON)
diff --git a/src/openexr/build_vars.cmake b/src/openexr/build_vars.cmake
index c4c880a..3ab27c8 100644
--- a/src/openexr/build_vars.cmake
+++ b/src/openexr/build_vars.cmake
@@ -1,5 +1,7 @@
 # add openexr if available
-find_package(OpenEXR QUIET)
+if(VSGXCHANGE_WITH_OPENEXR)
+find_package(OpenEXR REQUIRED)
+endif()
 
 if(OpenEXR_FOUND)
     OPTION(vsgXchange_openexr "Optional OpenEXR support provided" ON)