diff --git a/extern/CMakeProject-json.cmake b/extern/CMakeProject-json.cmake
index ec133ea2be..953a8d82d4 100644
--- a/extern/CMakeProject-json.cmake
+++ b/extern/CMakeProject-json.cmake
@@ -1,8 +1,6 @@
 if(WITH_SYSTEM_JSONCPP)
-  find_library(JSONCPP_LIBRARY jsoncpp)
-  if(JSONCPP_LIBRARY MATCHES "JSONCPP_LIBRARY-NOTFOUND")
-    message(FATAL_ERROR "Need jsoncpp.")
-  endif()
+  find_package(PkgConfig REQUIRED)
+  pkg_check_modules(JSONCPP REQUIRED jsoncpp)
 else()
   list(APPEND JSON_SRC
               "jsoncpp/src/lib_json/json_reader.cpp"
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index c29df4338d..72cb54a493 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -449,7 +449,7 @@ else()
 endif()
 
 if(WITH_SYSTEM_JSONCPP)
-  list(APPEND SMDATA_LINK_LIB ${JSONCPP_LIBRARY})
+  list(APPEND SMDATA_LINK_LIB ${JSONCPP_LIBRARIES})
 else()
   list(APPEND SMDATA_LINK_LIB "jsoncpp")
 endif()
@@ -612,10 +612,23 @@ list(APPEND SM_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR}
             "${SM_SRC_DIR}/generated")
 list(APPEND SM_INCLUDE_DIRS "${JPEG_INCLUDE_DIR}")
 if(NOT APPLE)
-  list(APPEND SM_INCLUDE_DIRS
-              "${SM_EXTERN_DIR}/glew-1.5.8/include"
-              "${SM_EXTERN_DIR}/jsoncpp/include"
-              "${SM_EXTERN_DIR}/zlib")
+  if(NOT WITH_SYSTEM_GLEW)
+    list(APPEND SM_INCLUDE_DIRS
+                "${SM_EXTERN_DIR}/glew-1.5.8/include")
+  endif()
+
+  if(WITH_SYSTEM_JSONCPP)
+    list(APPEND SM_INCLUDE_DIRS ${JSONCPP_INCLUDE_DIRS})
+  else()
+    list(APPEND SM_INCLUDE_DIRS
+                "${SM_EXTERN_DIR}/jsoncpp/include")
+  endif()
+
+  if(NOT WITH_SYSTEM_ZLIB)
+    list(APPEND SM_INCLUDE_DIRS
+                "${SM_EXTERN_DIR}/zlib")
+  endif()
+
   if(MSVC)
     if(WITH_OGG)
       list(APPEND SM_INCLUDE_DIRS
@@ -625,7 +638,7 @@ if(NOT APPLE)
     endif()
     list(APPEND SM_INCLUDE_DIRS "${SM_EXTERN_DIR}/ffmpeg/include")
   else()
-    if(WITH_OGG)
+    if(WITH_OGG AND NOT WITH_SYSTEM_OGG)
       list(APPEND SM_INCLUDE_DIRS "${SM_EXTERN_DIR}/vorbis")
     endif()
     if(HAS_FFMPEG)
@@ -664,7 +677,7 @@ endif()
 if(WIN32)
   # FIXME: This makes no sense...
   #list(APPEND SM_INCLUDE_DIRS ${DIRECTX_INCLUDE_DIR})
-else()
+elseif(NOT WITH_SYSTEM_PNG)
   list(APPEND SM_INCLUDE_DIRS "${SM_EXTERN_DIR}/libpng/include")
 endif()
 
diff --git a/src/CMakeProject-texture.cmake b/src/CMakeProject-texture.cmake
index 70ccd5ab16..c46cbe14f0 100644
--- a/src/CMakeProject-texture.cmake
+++ b/src/CMakeProject-texture.cmake
@@ -50,10 +50,18 @@ target_link_libraries("TextureFontGenerator" ${TEXTURE_LINK_LIB})
 list(APPEND TEXTURE_INCLUDE_DIRS
             "${TEXTURE_DIR}"
             "${TEXTURE_DIR}/res"
-            "${SM_EXTERN_DIR}/zlib"
-            "${SM_EXTERN_DIR}/libpng/include"
             "${SM_SRC_DIR}/generated")
 
+if(NOT WITH_SYSTEM_ZLIB)
+  list(APPEND TEXTURE_INCLUDE_DIRS
+              "${SM_EXTERN_DIR}/zlib")
+endif()
+
+if(NOT WITH_SYSTEM_PNG)
+  list(APPEND TEXTURE_INCLUDE_DIRS
+              "${SM_EXTERN_DIR}/libpng/include")
+endif()
+
 target_include_directories("TextureFontGenerator"
                            PUBLIC ${TEXTURE_INCLUDE_DIRS})