diff --git a/Arduino.mk b/Arduino.mk
index 50d60ee..77313c2 100644
--- a/Arduino.mk
+++ b/Arduino.mk
@@ -1045,7 +1045,7 @@ endif
 
 ifndef CFLAGS_STD
     ifeq ($(shell expr $(CC_VERNUM) '>' 490), 1)
-        CFLAGS_STD      = -std=gnu11 -flto -fno-fat-lto-objects -fdiagnostics-color
+        CFLAGS_STD      = -std=gnu11
     else
         CFLAGS_STD        =
     endif
@@ -1056,7 +1056,7 @@ endif
 
 ifndef CXXFLAGS_STD
     ifeq ($(shell expr $(CC_VERNUM) '>' 490), 1)
-        CXXFLAGS_STD      = -std=gnu++11 -fno-threadsafe-statics -flto -fno-devirtualize -fdiagnostics-color
+        CXXFLAGS_STD      = -std=gnu++11
     else
         CXXFLAGS_STD      =
     endif
@@ -1069,7 +1069,9 @@ CFLAGS        += $(CFLAGS_STD)
 CXXFLAGS      += -fpermissive -fno-exceptions $(CXXFLAGS_STD)
 ASFLAGS       += -x assembler-with-cpp
 ifeq ($(shell expr $(CC_VERNUM) '>' 490), 1)
-    ASFLAGS += -flto
+    ASFLAGS  += -flto
+    CXXFLAGS += -fno-threadsafe-statics -flto -fno-devirtualize -fdiagnostics-color
+    CFLAGS   += -flto -fno-fat-lto-objects -fdiagnostics-color
 endif
 LDFLAGS       += -$(MCU_FLAG_NAME)=$(MCU) -Wl,--gc-sections -O$(OPTIMIZATION_LEVEL)
 ifeq ($(shell expr $(CC_VERNUM) '>' 490), 1)
diff --git a/HISTORY.md b/HISTORY.md
index dd59802..973edc1 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -8,6 +8,7 @@ I tried to give credit whenever possible. If I have missed anyone, kindly add it
 - Fix: Add -fno-devirtualize flag to workaround g++ segfault bug (issue #486). (https://github.com/sej7278)
 - Fix: Quote the prefix tag in the space_pad_to function
 - Tweak: Set ARDMK_VERSION to 1.6 (https://github.com/sej7278)
+- Tweak: Move non-standard-related items from CxxFLAGS_STD to CxxFLAGS (issue #523) (https://github.com/sej7278)
 - New: Added -fdiagnostics-color to *STD flags (https://github.com/sej7278)
 
 ### 1.6.0 (2017-07-11)
diff --git a/arduino-mk-vars.md b/arduino-mk-vars.md
index 0df7a11..0f93c89 100644
--- a/arduino-mk-vars.md
+++ b/arduino-mk-vars.md
@@ -912,7 +912,7 @@ OTHER_LIBS = -lsomeplatformlib
 
 Controls, *exclusively*, which C standard is to be used for compilation.
 
-Defaults to `undefined` on 1.0.x or `-std=gnu11 -flto -fno-fat-lto-objects` on 1.5+ or if you install AVR toolchain > 4.9.0
+Defaults to `undefined` on 1.0.x or `-std=gnu11` on 1.5+ or if you install AVR toolchain > 4.9.0
 
 Possible values:
 
@@ -927,14 +927,14 @@ Possible values:
 	*	`-std=c11`
 	*	`-std=gnu89`
 	*	`-std=gnu99`
-	*	`-std=gnu11 -flto -fno-fat-lto-objects` - This is the default for C code
+	*	`-std=gnu11` - This is the default for C code
 
 For more information, please refer to the [Options Controlling C Dialect](https://gcc.gnu.org/onlinedocs/gcc/C-Dialect-Options.html)
 
 **Example:**
 
 ```Makefile
-CFLAGS_STD = = -std=gnu89
+CFLAGS_STD = -std=gnu89
 ```
 
 **Requirement:** *Optional*
@@ -947,7 +947,7 @@ CFLAGS_STD = = -std=gnu89
 
 Controls, *exclusively*, which C++ standard is to be used for compilation.
 
-Defaults to `undefined` on 1.0 or `-std=gnu++11 -fno-threadsafe-statics -flto` on AVR toolchain > 4.9.0 (e.g. IDE 1.6.10+)
+Defaults to `undefined` on 1.0 or `-std=gnu++11` on AVR toolchain > 4.9.0 (e.g. IDE 1.6.10+)
 
 Possible values:
 
@@ -964,7 +964,7 @@ Possible values:
 	*	`-std=c++1y`
 	*	`-std=c++14`
 	*	`-std=gnu++98`
-	*	`-std=gnu++11 -fno-threadsafe-statics -flto` - This is the default for C++ code
+	*	`-std=gnu++11` - This is the default for C++ code
 	*	`-std=gnu++1y`
 	*	`-std=gnu++14`
 
@@ -973,7 +973,7 @@ For more information, please refer to the [Options Controlling C Dialect](https:
 **Example:**
 
 ```Makefile
-CXXFLAGS_STD = = -std=gnu++98
+CXXFLAGS_STD = -std=gnu++98
 ```
 
 **Requirement:** *Optional*
@@ -987,7 +987,7 @@ CXXFLAGS_STD = = -std=gnu++98
 Flags passed to compiler for files compiled as C. Add more flags to this
 variable using `+=`.
 
-Defaults to all flags required for a typical build.
+Defaults to `undefined` on 1.0 or `-flto -fno-fat-lto-objects -fdiagnostics-color` on AVR toolchain > 4.9.0 (e.g. IDE 1.6.10+)
 
 **Example:**
 
@@ -1006,7 +1006,9 @@ CFLAGS += -my-c-only-flag
 Flags passed to the compiler for files compiled as C++. Add more flags to this
 variable using `+=`.
 
-Defaults to `-fpermissive -fno-exceptions`
+Defaults to `-fpermissive -fno-exceptions` on 1.0
+or `-fpermissive -fno-exceptions -fno-threadsafe-statics -flto -fno-devirtualize -fdiagnostics-color`
+on AVR toolchain > 4.9.0 (e.g. IDE 1.6.10+)
 
 **Example:**