diff --git a/build/GNUbasemsvc.mk b/build/GNUbasemsvc.mk
index 69bcbe8c..1ef6b911 100644
--- a/build/GNUbasemsvc.mk
+++ b/build/GNUbasemsvc.mk
@@ -26,12 +26,13 @@
 # TODO loads of warnings in the system header files
 # TODO /analyze requires us to write annotations everywhere
 # TODO undecided flags from qo?
+# -RTCc is not supplied because it's discouraged as of VS2015; see https://www.reddit.com/r/cpp/comments/46mhne/rtcc_rejects_conformant_code_with_visual_c_2015/d06auq5
 CFLAGS += \
 	-W4 \
 	-wd4100 \
 	-TC \
 	-bigobj -nologo \
-	-RTC1 -RTCc -RTCs -RTCu
+	-RTC1 -RTCs -RTCu
 
 # TODO prune these
 # -EHsc is to shut the compiler up in some cases
@@ -40,7 +41,7 @@ CXXFLAGS += \
 	-wd4100 \
 	-TP \
 	-bigobj -nologo \
-	-RTC1 -RTCc -RTCs -RTCu \
+	-RTC1 -RTCs -RTCu \
 	-EHsc
 
 # TODO warnings on undefined symbols
diff --git a/windows/areadraw.cpp b/windows/areadraw.cpp
index 90a8fe28..77e9aeaf 100644
--- a/windows/areadraw.cpp
+++ b/windows/areadraw.cpp
@@ -44,6 +44,7 @@ static HRESULT doPaint(uiArea *a, ID2D1RenderTarget *rt, RECT *clip)
 	bgcolor.r = ((float) GetRValue(bgcolorref)) / 255.0;
 	// due to utter apathy on Microsoft's part, GetGValue() does not work with MSVC's Run-Time Error Checks
 	// it has not worked since 2008 and they have *never* fixed it
+	// TODO now that -RTCc has just been deprecated entirely, should we switch back?
 	bgcolor.g = ((float) ((BYTE) ((bgcolorref & 0xFF00) >> 8))) / 255.0;
 	bgcolor.b = ((float) GetBValue(bgcolorref)) / 255.0;
 	bgcolor.a = 1.0;
diff --git a/windows/d2dscratch.cpp b/windows/d2dscratch.cpp
index 06f49a41..f9504317 100644
--- a/windows/d2dscratch.cpp
+++ b/windows/d2dscratch.cpp
@@ -26,6 +26,7 @@ static HRESULT d2dScratchDoPaint(HWND hwnd, ID2D1RenderTarget *rt)
 	bgcolor.r = ((float) GetRValue(bgcolorref)) / 255.0;
 	// due to utter apathy on Microsoft's part, GetGValue() does not work with MSVC's Run-Time Error Checks
 	// it has not worked since 2008 and they have *never* fixed it
+	// TODO now that -RTCc has just been deprecated entirely, should we switch back?
 	bgcolor.g = ((float) ((BYTE) ((bgcolorref & 0xFF00) >> 8))) / 255.0;
 	bgcolor.b = ((float) GetBValue(bgcolorref)) / 255.0;
 	bgcolor.a = 1.0;