diff --git a/CMakeLists.txt b/CMakeLists.txt
index ef92706..fee22e4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -129,6 +129,9 @@ if(SIMAGE_USE_GDIPLUS)
     }
   " GDIPLUS_FOUND)
   unset(CMAKE_REQUIRED_LIBRARIES)
+  if(NOT GDIPLUS_FOUND)
+    message(FATAL_ERROR "GDI+ is required on Windows.")
+  endif()
 endif()
 if(SIMAGE_USE_AVIENC)
   set(CMAKE_REQUIRED_LIBRARIES vfw32)
@@ -142,6 +145,9 @@ if(SIMAGE_USE_AVIENC)
     }
   " VFW_FOUND)
   unset(CMAKE_REQUIRED_LIBRARIES)
+  if(NOT VFW_FOUND)
+  	message(FATAL_ERROR "Video for Windows is required on Windows.")
+  endif()
 endif()
 
 # On macOS QuickTime supports BMP, GIF, JPEG, JPEG 2000, PNG, TIFF, and TGA.
@@ -286,7 +292,7 @@ if(SIMAGE_OGGVORBIS_SUPPORT)
   find_package(Ogg REQUIRED)
   find_package(Vorbis REQUIRED)
   if(OGG_FOUND)
-    find_package(Opus)
+    find_package(Opus REQUIRED)
   endif()
 endif()
 
@@ -306,8 +312,8 @@ if(NOT SIMAGE_QUICKTIME_SUPPORT AND NOT SIMAGE_CGIMAGE_SUPPORT AND NOT SIMAGE_GD
   if(SIMAGE_TIFF_SUPPORT)
     find_package(TIFF REQUIRED)
     if(TIFF_FOUND)
-      find_package(LibLZMA)
-      find_package(Zstd)
+      find_package(LibLZMA REQUIRED)
+      find_package(Zstd REQUIRED)
     endif()
   endif()