diff --git a/external/CMakeLists.txt b/external/CMakeLists.txt
index 349350d33..46c5e0267 100644
--- a/external/CMakeLists.txt
+++ b/external/CMakeLists.txt
@@ -208,8 +208,13 @@ else()
     set(USE_PRECOMPILED_LIBS TRUE)
 endif()
 
-# We don't CACHE for _DEPENDS variable, as the external project is only added when NOT _FOUND
-# Use PARENT_SCOPE so they can still be used in other CMakeFiles
+# We don't CACHE the _DEPENDS variables, as the external project is only added when NOT _FOUND
+# and not in subsequent configures when _FOUND
+# Use PARENT_SCOPE so they can still be used in other CMakeFiles.
+macro(set_global NAME VALUE)
+    set(${NAME} ${VALUE})
+    set(${NAME} ${VALUE} PARENT_SCOPE)
+endmacro()
 
 if (NOT LIBUSB_FOUND AND NOT USE_PRECOMPILED_LIBS)
     # Cloning git repo doesn't include configure, so we download the bz2 which does
@@ -221,7 +226,7 @@ if (NOT LIBUSB_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(libusb install_dir)
-    set(LIBUSB_DEPENDS libusb PARENT_SCOPE)
+    set_global(LIBUSB_DEPENDS libusb)
     set(LIBUSB_FOUND ON CACHE INTERNAL "")
     set(LIBUSB_EXTERNAL ON CACHE INTERNAL "")
     set(LIBUSB_INCLUDE_DIR "${install_dir}/include/libusb-1.0" CACHE INTERNAL "")
@@ -243,7 +248,7 @@ if (NOT HIDAPI_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(hidapi install_dir)
-    set(HIDAPI_DEPENDS hidapi PARENT_SCOPE)
+    set_global(HIDAPI_DEPENDS hidapi)
     set(HIDAPI_FOUND ON CACHE INTERNAL "")
     set(HIDAPI_EXTERNAL ON CACHE INTERNAL "")
     set(HIDAPI_ROOT_DIR "${install_dir}" CACHE INTERNAL "")
@@ -263,7 +268,7 @@ if (NOT OPUS_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(opus install_dir)
-    set(OPUS_DEPENDS opus PARENT_SCOPE)
+    set_global(OPUS_DEPENDS opus)
     set(OPUS_FOUND ON CACHE INTERNAL "")
     set(OPUS_EXTERNAL ON CACHE INTERNAL "")
     set(OPUS_INCLUDE_DIRS "${install_dir}/include" CACHE INTERNAL "")
@@ -286,7 +291,7 @@ if (NOT ZLIB_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(zlib install_dir)
-    set(ZLIB_DEPENDS zlib PARENT_SCOPE)
+    set_global(ZLIB_DEPENDS zlib)
     set(ZLIB_FOUND ON CACHE INTERNAL "")
     set(ZLIB_EXTERNAL ON CACHE INTERNAL "")
     set(ZLIB_INCLUDE_DIRS "${install_dir}/include" CACHE INTERNAL "")
@@ -308,7 +313,7 @@ if (NOT FAAD_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(faad source_dir binary_dir install_dir)
-    set(FAAD_DEPENDS faad PARENT_SCOPE)
+    set_global(FAAD_DEPENDS faad)
     set(FAAD_FOUND ON CACHE INTERNAL "")
     set(FAAD_EXTERNAL ON CACHE INTERNAL "")
     set(FAAD_INCLUDE_DIR "${install_dir}/include" CACHE INTERNAL "")
@@ -332,7 +337,7 @@ if (NOT FFTW3F_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(fftw3f source_dir binary_dir)
-    set(FFTW3F_DEPENDS fftw3f PARENT_SCOPE)
+    set_global(FFTW3F_DEPENDS fftw3f)
     set(FFTW3F_FOUND ON CACHE INTERNAL "")
     set(FFTW3F_EXTERNAL ON CACHE INTERNAL "")
     set(FFTW3F_INCLUDE_DIRS "${source_dir}/api" "${binary_dir}" CACHE INTERNAL "")
@@ -415,7 +420,7 @@ if (NOT FFMEG_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
         ExternalProject_Get_Property(x264 install_dir)
-        set(X264_DEPENDS x264 PARENT_SCOPE)
+        set_global(X264_DEPENDS x264)
         set(X264_PKG_CONFIG_DIR "${install_dir}/lib/pkgconfig")
         set(X264_FOUND ON CACHE INTERNAL "")
         set(X264_EXTERNAL ON CACHE INTERNAL "")
@@ -433,7 +438,7 @@ if (NOT FFMEG_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
         ExternalProject_Get_Property(x265 install_dir)
-        set(X265_DEPENDS x265 PARENT_SCOPE)
+        set_global(X265_DEPENDS x265)
         set(X265_PKG_CONFIG_DIR "${install_dir}/lib/pkgconfig")
         set(X265_FOUND ON CACHE INTERNAL "")
         set(X265_EXTERNAL ON CACHE INTERNAL "")
@@ -450,7 +455,7 @@ if (NOT FFMEG_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
         ExternalProject_Get_Property(fdk_aac install_dir)
-        set(FDK_AAC_DEPENDS fdk_aac PARENT_SCOPE)
+        set_global(FDK_AAC_DEPENDS fdk_aac)
         set(FDK_AAC_PKG_CONFIG_DIR "${install_dir}/lib/pkgconfig")
         set(FDK_AAC_FOUND ON CACHE INTERNAL "")
         set(FDK_AAC_EXTERNAL ON CACHE INTERNAL "")
@@ -469,7 +474,7 @@ if (NOT FFMEG_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
         ExternalProject_Get_Property(mpg123 install_dir)
-        set(MPG123_DEPENDS mpg123 PARENT_SCOPE)
+        set_global(MPG123_DEPENDS mpg123)
         set(MPG123_PKG_CONFIG_DIR "${install_dir}/lib/pkgconfig")
         set(MPG123_FOUND ON CACHE INTERNAL "")
         set(MPG123_EXTERNAL ON CACHE INTERNAL "")
@@ -489,7 +494,7 @@ if (NOT FFMEG_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
         ExternalProject_Get_Property(lame install_dir)
-        set(LAME_DEPENDS lame PARENT_SCOPE)
+        set_global(LAME_DEPENDS lame)
         # ffmpeg doesn't try to use pkg-config for lame, as it doesn't include a .pc file
         #set(LAME_PKG_CONFIG_DIR "${install_dir}/lib/pkgconfig")
         set(LAME_EXTRA_CFLAGS "-I${install_dir}/include")
@@ -513,7 +518,7 @@ if (NOT FFMEG_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(ffmpeg install_dir)
-    set(FFMPEG_DEPENDS ffmpeg PARENT_SCOPE)
+    set_global(FFMPEG_DEPENDS ffmpeg)
     set(FFMPEG_INSTALL_DIR "${install_dir}")
     set(FFMPEG_FOUND ON CACHE INTERNAL "")
     set(FFMPEG_EXTERNAL ON CACHE INTERNAL "")
@@ -545,7 +550,7 @@ if (NOT OpenCV_FOUND AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(opencv source_dir binary_dir)
-    set(OpenCV_DEPENDS opencv PARENT_SCOPE)
+    set_global(OpenCV_DEPENDS opencv)
     set(OpenCV_FOUND ON CACHE INTERNAL "")
     set(OpenCV_EXTERNAL ON CACHE INTERNAL "")
     set(OpenCV_INCLUDE_DIRS
@@ -600,7 +605,7 @@ if ((NOT CODEC2_FOUND OR CODEC2_EXTERNAL) AND NOT USE_PRECOMPILED_LIBS)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(codec2 source_dir binary_dir)
-    set(CODEC2_DEPENDS codec2 PARENT_SCOPE)
+    set_global(CODEC2_DEPENDS codec2)
     set(CODEC2_FOUND ON CACHE INTERNAL "")
     set(CODEC2_EXTERNAL ON CACHE INTERNAL "")
     set(CODEC2_INCLUDE_DIR "${source_dir}/src" "${binary_dir}" CACHE INTERNAL "")
@@ -641,7 +646,7 @@ if (NOT CM256CC_FOUND OR CM256CC_EXTERNAL)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(cm256cc source_dir binary_dir)
-    set(CM256CC_DEPENDS cm256cc PARENT_SCOPE)
+    set_global(CM256CC_DEPENDS cm256cc)
     set(CM256CC_FOUND ON CACHE INTERNAL "")
     set(CM256CC_EXTERNAL ON CACHE INTERNAL "")
     # we need cm256cc/library.h
@@ -674,7 +679,7 @@ if ((NOT LIBDSDCC_FOUND OR LIBDSDCC_EXTERNAL) AND (NOT LIBMBE_FOUND OR LIBMBE_EX
             )
     ExternalProject_Get_Property(mbelib source_dir binary_dir)
     set(USE_MBELIB ON)
-    set(DSDCC_DEPENDS mbelib PARENT_SCOPE)
+    set_global(DSDCC_DEPENDS mbelib)
     set(LIBMBE_FOUND ON CACHE INTERNAL "")
     set(LIBMBE_EXTERNAL ON CACHE INTERNAL "")
     set(LIBMBE_INCLUDE_DIR "${source_dir}" CACHE INTERNAL "")
@@ -705,7 +710,7 @@ if (NOT LIBSERIALDV_FOUND OR LIBSERIALDV_EXTERNAL)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(serialdv source_dir binary_dir)
-    set(DSDCC_DEPENDS ${DSDCC_DEPENDS} serialdv PARENT_SCOPE)
+    set_global(DSDCC_DEPENDS ${DSDCC_DEPENDS} serialdv)
     set(LIBSERIALDV_FOUND ON CACHE INTERNAL "")
     set(LIBSERIALDV_EXTERNAL ON CACHE INTERNAL "")
     set(LIBSERIALDV_INCLUDE_DIR "${source_dir}" CACHE INTERNAL "")
@@ -837,7 +842,7 @@ if (WIN32)
             TEST_COMMAND ""
             )
     ExternalProject_Get_Property(pthreads4w source_dir binary_dir)
-    set(PTHREADS4W_DEPENDS pthreads4w PARENT_SCOPE)
+    set_global(PTHREADS4W_DEPENDS pthreads4w)
     set(PTHREADS4W_FOUND ON CACHE INTERNAL "")
     set(PTHREADS4W_EXTERNAL ON CACHE INTERNAL "")
     set(PTHREADS4W_INCLUDE_DIR "${source_dir}" CACHE INTERNAL "")
@@ -894,7 +899,7 @@ if (ZLIB_FOUND AND FAAD_FOUND)
                 )
     endif(WIN32)
     ExternalProject_Get_Property(dab source_dir binary_dir)
-    set(DAB_DEPENDS dab PARENT_SCOPE)
+    set_global(DAB_DEPENDS dab)
     set(DAB_FOUND ON CACHE INTERNAL "")
     set(DAB_EXTERNAL ON CACHE INTERNAL "")
     set(DAB_INCLUDE_DIR "${EXTERNAL_BUILD_LIBRARIES}/dab/src/dab" CACHE INTERNAL "")
@@ -1334,7 +1339,7 @@ if (WIN32 OR APPLE)
                     )
         endif ()
         ExternalProject_Get_Property(libxml2 source_dir binary_dir)
-        set(LIBXML2_DEPENDS libxml2 PARENT_SCOPE)
+        set_global(LIBXML2_DEPENDS libxml2)
         set(LIBXML2_FOUND ON CACHE INTERNAL "")
         set(LIBXML2_EXTERNAL ON CACHE INTERNAL "")
         set(LIBXML2_INCLUDE_DIR "${source_dir}/include" CACHE INTERNAL "")