diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6e5d9cc400..22bc0e7cc5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,9 +10,9 @@ ENDIF( NOT CMAKE_BUILD_TYPE )
 set( ZDOOM_OUTPUT_DIR ${CMAKE_BINARY_DIR} CACHE PATH "Directory where zdoom.pk3 and the executable will be created." )
 set( ZDOOM_EXE_NAME "zdoom" CACHE FILEPATH "Name of the executable to create." )
 
-if( CMAKE_COMPILER_IS_GNUCXX )
+if( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 	set( PROFILE 0 CACHE BOOL "Enable profiling with gprof for Debug and RelWithDebInfo build types." )
-endif( CMAKE_COMPILER_IS_GNUCXX )
+endif( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 
 set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}")
 
diff --git a/bzip2/CMakeLists.txt b/bzip2/CMakeLists.txt
index 5c1255604b..6006f491cb 100644
--- a/bzip2/CMakeLists.txt
+++ b/bzip2/CMakeLists.txt
@@ -1,8 +1,8 @@
 cmake_minimum_required( VERSION 2.4 )
 
-if( CMAKE_COMPILER_IS_GNUC )
+if( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" )
 	set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -fomit-frame-pointer" )
-endif( CMAKE_COMPILER_IS_GNUC )
+endif( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" )
 
 add_definitions( -DBZ_NO_STDIO )
 add_library( bz2
diff --git a/dumb/CMakeLists.txt b/dumb/CMakeLists.txt
index 591e314002..ee50c4a0af 100644
--- a/dumb/CMakeLists.txt
+++ b/dumb/CMakeLists.txt
@@ -11,9 +11,9 @@ endif( NOT CMAKE_BUILD_TYPE MATCHES "Release" )
 
 set( CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -D_DEBUG -DDEBUGMODE=1" )
 
-if( CMAKE_COMPILER_IS_GNUC )
+if( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" )
 	set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wno-pointer-sign -Wno-uninitialized" )
-endif( CMAKE_COMPILER_IS_GNUC )
+endif( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" )
 
 CHECK_FUNCTION_EXISTS( itoa ITOA_EXISTS )
 if( NOT ITOA_EXISTS )
@@ -101,6 +101,6 @@ add_library( dumb
     src/it/xmeffect.c )
 target_link_libraries( dumb )
 
-if( CMAKE_COMPILER_IS_GNUCXX )
+if( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 	set_source_files_properties( src/it/filter.cpp PROPERTIES COMPILE_FLAGS -msse )
-endif( CMAKE_COMPILER_IS_GNUCXX )
+endif( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
diff --git a/game-music-emu/CMakeLists.txt b/game-music-emu/CMakeLists.txt
index 7905f847ab..5c4a030434 100644
--- a/game-music-emu/CMakeLists.txt
+++ b/game-music-emu/CMakeLists.txt
@@ -6,7 +6,7 @@ if( NOT CMAKE_BUILD_TYPE MATCHES "Release" )
 	set( CMAKE_BUILD_TYPE "RelWithDebInfo" )
 endif( NOT CMAKE_BUILD_TYPE MATCHES "Release" )
 
-if( CMAKE_COMPILER_IS_GNUCXX )
+if( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 	set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra" )
 	if( NOT PROFILE )
 		set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fomit-frame-pointer" )
@@ -15,7 +15,7 @@ if( CMAKE_COMPILER_IS_GNUCXX )
 	if( HAVE_NO_ARRAY_BOUNDS )
 		set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-array-bounds" )
 	endif( HAVE_NO_ARRAY_BOUNDS )
-endif( CMAKE_COMPILER_IS_GNUCXX )
+endif( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 
 add_library( gme
     gme/Blip_Buffer.cpp
diff --git a/gdtoa/CMakeLists.txt b/gdtoa/CMakeLists.txt
index 6fc394d8d4..4ad0be6de9 100644
--- a/gdtoa/CMakeLists.txt
+++ b/gdtoa/CMakeLists.txt
@@ -8,9 +8,9 @@ if( MSVC )
 	set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /wd4554 /wd4102" )
 endif( MSVC )
 
-if( CMAKE_COMPILER_IS_GNUCXX )
+if( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 	set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra" )
-endif( CMAKE_COMPILER_IS_GNUCXX )
+endif( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 
 include_directories( ${CMAKE_CURRENT_BINARY_DIR} )
 add_definitions( -DINFNAN_CHECK -DMULTIPLE_THREADS )
diff --git a/jpeg-6b/CMakeLists.txt b/jpeg-6b/CMakeLists.txt
index c3a5f458c6..5c8b5972e5 100644
--- a/jpeg-6b/CMakeLists.txt
+++ b/jpeg-6b/CMakeLists.txt
@@ -1,8 +1,8 @@
 cmake_minimum_required( VERSION 2.4 )
 
-if( CMAKE_COMPILER_IS_GNUC )
+if( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" )
 	set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -fomit-frame-pointer" )
-endif( CMAKE_COMPILER_IS_GNUC )
+endif( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" )
 
 add_library( jpeg
     jcomapi.c
diff --git a/lzma/CMakeLists.txt b/lzma/CMakeLists.txt
index 6a2561c68c..7582712fea 100644
--- a/lzma/CMakeLists.txt
+++ b/lzma/CMakeLists.txt
@@ -1,8 +1,8 @@
 cmake_minimum_required( VERSION 2.4 )
 
-if( CMAKE_COMPILER_IS_GNUC )
+if( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" )
 	set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -fomit-frame-pointer" )
-endif( CMAKE_COMPILER_IS_GNUC )
+endif( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" )
 
 set( LZMA_FILES
 	C/Archive/7z/7zDecode.c
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 9436154bb0..08f8e0ba64 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -10,14 +10,14 @@ include( CheckCXXCompilerFlag )
 include( FindPkgConfig )
 
 option( NO_ASM "Disable assembly code" )
-if( CMAKE_COMPILER_IS_GNUCXX )
+if( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 	option( NO_STRIP "Do not strip Release or MinSizeRel builds" )
 	# At least some versions of Xcode fail if you strip with the linker
 	# instead of the separate strip utility.
 	if( APPLE )
 		set( NO_STRIP ON )
 	endif( APPLE )
-endif( CMAKE_COMPILER_IS_GNUCXX )
+endif( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 
 option( DYN_FLUIDSYNTH "Dynamically load fluidsynth" )
 
@@ -391,7 +391,7 @@ endif( SSE_MATTERS )
 
 # Set up flags for GCC
 
-if( CMAKE_COMPILER_IS_GNUCXX )
+if( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 	if( PROFILE )
 		set( CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -pg" )
 		set( CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -pg" )
@@ -420,7 +420,7 @@ if( CMAKE_COMPILER_IS_GNUCXX )
 		set (CMAKE_EXE_LINKER_FLAGS_RELEASE "${CMAKE_EXE_LINKER_FLAGS_RELEASE} -s" )
 		set (CMAKE_EXE_LINKER_FLAGS_MINSIZEREL "${CMAKE_EXE_LINKER_FLAGS_MINSIZEREL} -s" )
 	endif( NOT NO_STRIP )
-endif( CMAKE_COMPILER_IS_GNUCXX )
+endif( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 
 # Check for functions that may or may not exist.
 
@@ -529,15 +529,15 @@ if( WIN32 )
 		win32/i_system.cpp
 		win32/st_start.cpp
 		win32/win32video.cpp )
-	if( CMAKE_COMPILER_IS_GNUCXX )
+	if( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 		# CMake is not set up to compile and link rc files with GCC. :(
 		add_custom_command( OUTPUT zdoom-rc.o
 			COMMAND windres -o zdoom-rc.o -i ${CMAKE_CURRENT_SOURCE_DIR}/win32/zdoom.rc
 			DEPENDS win32/zdoom.rc )
 		set( SYSTEM_SOURCES ${SYSTEM_SOURCES} zdoom-rc.o )
-	else( CMAKE_COMPILER_IS_GNUCXX )
+	else( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 		set( SYSTEM_SOURCES ${SYSTEM_SOURCES} win32/zdoom.rc )
-	endif( CMAKE_COMPILER_IS_GNUCXX )
+	endif( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 else( WIN32 )
 	set( SYSTEM_SOURCES_DIR sdl )
 	set( SYSTEM_SOURCES
@@ -980,7 +980,7 @@ if( NOT WIN32 )
 		COMMAND chmod +x ${CMAKE_CURRENT_BINARY_DIR}/link-make
 		COMMAND /bin/sh -c ${CMAKE_CURRENT_BINARY_DIR}/link-make )
 endif( NOT WIN32 )
-if( CMAKE_COMPILER_IS_GNUCXX )
+if( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 	# GCC misoptimizes this file
 	set_source_files_properties( oplsynth/fmopl.cpp PROPERTIES COMPILE_FLAGS "-fno-tree-dominator-opts -fno-tree-fre" )
 
@@ -988,7 +988,7 @@ if( CMAKE_COMPILER_IS_GNUCXX )
 	if( SSE_MATTERS )
 		set_source_files_properties( x86.cpp PROPERTIES COMPILE_FLAGS "-msse2 -mmmx" )
 	endif( SSE_MATTERS )
-endif( CMAKE_COMPILER_IS_GNUCXX )
+endif( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 
 if( MSVC )
 	set_target_properties(zdoom PROPERTIES LINK_FLAGS "/MANIFEST:NO")
diff --git a/tools/updaterevision/CMakeLists.txt b/tools/updaterevision/CMakeLists.txt
index aeacf01f39..d985b9e3f0 100644
--- a/tools/updaterevision/CMakeLists.txt
+++ b/tools/updaterevision/CMakeLists.txt
@@ -1,12 +1,12 @@
 cmake_minimum_required( VERSION 2.4 )
 
 if( WIN32 )
-	if( CMAKE_COMPILER_IS_GNUC OR CMAKE_COMPILER_IS_GNUCXX )
+	if( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 		add_custom_command( OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/trustinfo.o
 			COMMAND windres -o ${CMAKE_CURRENT_BINARY_DIR}/trustinfo.o -i ${CMAKE_CURRENT_SOURCE_DIR}/trustinfo.rc
 			DEPENDS trustinfo.rc )
 		set( TRUSTINFO trustinfo.o )
-	else( CMAKE_COMPILER_IS_GNUC OR CMAKE_COMPILER_IS_GNUCXX )
+	else( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 		if( MSVC_VERSION GREATER 1399 )
 			# VC 8+ adds a manifest automatically to the executable. We need to
 			# merge ours with it.
@@ -14,7 +14,7 @@ if( WIN32 )
 		else( MSVC_VERSION GREATER 1399 )
 			set( TRUSTINFO trustinfo.rc )
 		endif( MSVC_VERSION GREATER 1399 )
-	endif( CMAKE_COMPILER_IS_GNUC OR CMAKE_COMPILER_IS_GNUCXX )
+	endif( "${CMAKE_C_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" )
 endif( WIN32 )
 
 add_executable( updaterevision updaterevision.c ${TRUSTINFO} )