diff --git a/CMakeLists.txt b/CMakeLists.txt
index 547fe4d..1cdc737 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,16 +10,17 @@ set (STATIC_BUILD true)
 
 # It's an hack in order to be able to link statically planetblupi on darwin.
 if (APPLE)
-  set (CMAKE_LDFLAGS "-L${CMAKE_BINARY_DIR}/lib -framework AudioToolBox -framework AudioUnit -framework CoreAudio -framework CoreFoundation -framework Cocoa -framework OpenGL -framework IOKit -framework CoreVideo -framework Carbon")
+  set (ISAPPLE 1)
+  set (CMD_LDFLAGS "-L${CMAKE_BINARY_DIR}/lib -framework AudioToolBox -framework AudioUnit -framework CoreAudio -framework CoreFoundation -framework Cocoa -framework OpenGL -framework IOKit -framework CoreVideo -framework Carbon")
 
   if (OLD_SDK)
     set (OSX_SDK_VERSION 10.9)
     set (CMAKE_OSX_SYSROOT "/Developer/SDKs/MacOSX${OSX_SDK_VERSION}.sdk/")
     set (CMAKE_OSX_DEPLOYMENT_TARGET ${OSX_SDK_VERSION})
-    set (CMAKE_CXX_FLAGS "--sysroot ${CMAKE_OSX_SYSROOT} -mmacosx-version-min=${OSX_SDK_VERSION} ${CMAKE_CXX_FLAGS}")
-    set (CMAKE_C_FLAGS "--sysroot ${CMAKE_OSX_SYSROOT} -mmacosx-version-min=${OSX_SDK_VERSION} ${CMAKE_C_FLAGS}")
+    set (CMD_CXXFLAGS "--sysroot ${CMAKE_OSX_SYSROOT} -mmacosx-version-min=${OSX_SDK_VERSION} ${CMAKE_CXX_FLAGS}")
+    set (CMD_CFLAGS "--sysroot ${CMAKE_OSX_SYSROOT} -mmacosx-version-min=${OSX_SDK_VERSION} ${CMAKE_C_FLAGS}")
   endif ()
-  set (CMAKE_CPP_FLAGS "-I${CMAKE_BINARY_DIR}/include")
+  set (CMD_CPPFLAGS "-I${CMAKE_BINARY_DIR}/include")
 endif ()
 
 configure_file (cmd.sh.in cmd.sh @ONLY)
@@ -163,7 +164,7 @@ ExternalProject_Add (gettext_Project
 #########
 
 ExternalProject_Add (libpng_Project
-  URL http://prdownloads.sourceforge.net/libpng/libpng-1.6.28.tar.xz?download
+  URL http://prdownloads.sourceforge.net/libpng/libpng-1.6.28.tar.xz
   PREFIX ${CMAKE_BINARY_DIR}
   CONFIGURE_COMMAND ${CMD} ./configure
     --prefix=${CMAKE_BINARY_DIR}
diff --git a/cmd.sh.in b/cmd.sh.in
index 078d923..211fbda 100755
--- a/cmd.sh.in
+++ b/cmd.sh.in
@@ -4,10 +4,13 @@ export PKG_CONFIG_PATH="@CMAKE_BINARY_DIR@/lib/pkgconfig"
 export INCLUDE_PATH="@CMAKE_BINARY_DIR@/include"
 export LIBRARY_PATH="@CMAKE_BINARY_DIR@/lib"
 export BINARY_PATH="@CMAKE_BINARY_DIR@/bin"
-export LDFLAGS="@CMAKE_LDFLAGS@"
-export CXXFLAGS="@CMAKE_CXX_FLAGS@"
-export CFLAGS="@CMAKE_C_FLAGS@"
-export CPPFLAGS="@CMAKE_CPP_FLAGS@"
+
+if [ "@ISAPPLE@" = "1" ]; then
+  export LDFLAGS="$LDFLAGS @CMD_LDFLAGS@"
+  export CXXFLAGS="$CXXFLAGS @CMD_CXXFLAGS@"
+  export CFLAGS="$CFLAGS @CMD_CFLAGS@"
+  export CPPFLAGS="$CPPFLAGS @CMD_CPPFLAGS@"
+fi
 
 cmd=$1
 shift
diff --git a/planetblupi b/planetblupi
index 9b052fa..2b73637 160000
--- a/planetblupi
+++ b/planetblupi
@@ -1 +1 @@
-Subproject commit 9b052fa8a2877ef150e1c7f28fcc4802900fcb49
+Subproject commit 2b73637748f8b4e872483ff2813cc000a4a57a6b