diff --git a/externals/Makefile b/externals/Makefile
index 363736cf..93833acd 100644
--- a/externals/Makefile
+++ b/externals/Makefile
@@ -675,6 +675,10 @@ $(gem_src)/Gem.pd_linux: $(gem_src)/configure
 	test -s $(gem_src)/Gem.pd_linux || \
 		cd $(gem_src) && ./configure \
 			CXXFLAGS="-DHAVE_S_STUFF_H $(CFLAGS_ADD)" \
+			PKG_IMAGEMAGICK___CFLAGS="$(shell PKG_CONFIG_PATH=/usr/lib/imagemagick6/pkgconfig pkg-config --cflags ImageMagick-6.Q16HDRI)" \
+			PKG_IMAGEMAGICK___LIBS="$(shell PKG_CONFIG_PATH=/usr/lib/imagemagick6/pkgconfig pkg-config --libs ImageMagick-6.Q16HDRI)" \
+			PKG_MAGICKCORE_CFLAGS="$(shell PKG_CONFIG_PATH=/usr/lib/imagemagick6/pkgconfig pkg-config --cflags MagickCore-6.Q16HDRI)" \
+			PKG_MAGICKCORE_LIBS="$(shell PKG_CONFIG_PATH=/usr/lib/imagemagick6/pkgconfig pkg-config --libs MagickCore-6.Q16HDRI)" \
 			--prefix=$(prefix) \
 			--with-video=plugins \
 			--with-film=plugins \