diff --git a/CMakeLists.txt b/CMakeLists.txt
index 254a750a6..61c4e228f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -99,6 +99,10 @@ ELSEIF(CMAKE_SYSTEM_PROCESSOR STREQUAL "AMD64" OR CMAKE_SYSTEM_PROCESSOR STREQUA
 
 ENDIF()
 
+# Work around CMAKE_INSTALL_PREFIX being a relative directory when using -B
+# on Windows, which in turn trips up 'file(RELATIVE_PATH ...)' used in SDL2
+set(CMAKE_INSTALL_PREFIX ${CMAKE_CURRENT_BINARY_DIR}/extern/install)
+
 add_subdirectory(extern)
 
 link_directories(.)
diff --git a/extern/SDL2 b/extern/SDL2
index fd196c446..f17058b56 160000
--- a/extern/SDL2
+++ b/extern/SDL2
@@ -1 +1 @@
-Subproject commit fd196c446a476282dd457fbafe9e9b3feae3f370
+Subproject commit f17058b562c8a1090c0c996b42982721ace90903