diff --git a/cmake/px4_add_common_flags.cmake b/cmake/px4_add_common_flags.cmake
index 0958b13465..a486089d8f 100644
--- a/cmake/px4_add_common_flags.cmake
+++ b/cmake/px4_add_common_flags.cmake
@@ -79,6 +79,8 @@ function(px4_add_common_flags)
 		-Wunknown-pragmas
 		-Wunused-variable
 
+		#-Wcast-align # TODO: fix and enable
+
 		# disabled warnings
 		-Wno-implicit-fallthrough # set appropriate level and update
 		-Wno-missing-field-initializers
@@ -97,7 +99,7 @@ function(px4_add_common_flags)
 			add_compile_options(
 				-Qunused-arguments
 
-				-Wno-address-of-packed-member
+				-Wno-address-of-packed-member # TODO: fix and enable (mavlink, etc)
 				-Wno-unknown-warning-option
 				-Wno-unused-const-variable
 				-Wno-varargs
@@ -111,6 +113,10 @@ function(px4_add_common_flags)
 			add_compile_options(-fdiagnostics-color=always)
 		endif()
 
+		if(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 9)
+			add_compile_options(-Wno-address-of-packed-member) # TODO: fix and enable (mavlink, etc)
+		endif()
+
 		add_compile_options(
 			-fno-builtin-printf
 			-fno-strength-reduce
diff --git a/src/lib/mathlib/math/Limits.hpp b/src/lib/mathlib/math/Limits.hpp
index cab5d98707..39ce00fce0 100644
--- a/src/lib/mathlib/math/Limits.hpp
+++ b/src/lib/mathlib/math/Limits.hpp
@@ -47,71 +47,60 @@
 #define MATH_PI		3.141592653589793238462643383280
 #endif
 
-//this should be defined in stdint.h, but seems to be missing in the ARM toolchain (5.2.0)
-#ifndef UINT64_C
-# if __WORDSIZE == 64
-#  define UINT64_C(c)	c ## UL
-# else
-#  define UINT64_C(c)	c ## ULL
-# endif
-#endif
-
-
 namespace math
 {
 
 template<typename _Tp>
-constexpr const _Tp &min(const _Tp &a, const _Tp &b)
+constexpr _Tp min(_Tp a, _Tp b)
 {
 	return (a < b) ? a : b;
 }
 
 template<typename _Tp>
-constexpr const _Tp &max(const _Tp &a, const _Tp &b)
+constexpr _Tp max(_Tp a, _Tp b)
 {
 	return (a > b) ? a : b;
 }
 
 template<typename _Tp>
-constexpr const _Tp &constrain(const _Tp &val, const _Tp &min_val, const _Tp &max_val)
+constexpr _Tp constrain(_Tp val, _Tp min_val, _Tp max_val)
 {
 	return (val < min_val) ? min_val : ((val > max_val) ? max_val : val);
 }
 
 /** Constrain float values to valid values for int16_t.
  * Invalid values are just clipped to be in the range for int16_t. */
-inline int16_t constrainFloatToInt16(float value)
+constexpr int16_t constrainFloatToInt16(float value)
 {
 	return (int16_t)math::constrain(value, (float)INT16_MIN, (float)INT16_MAX);
 }
 
-
 template<typename _Tp>
-inline constexpr bool isInRange(const _Tp &val, const _Tp &min_val, const _Tp &max_val)
+constexpr bool isInRange(_Tp val, _Tp min_val, _Tp max_val)
 {
 	return (min_val <= val) && (val <= max_val);
 }
 
 template<typename T>
-constexpr T radians(const T degrees)
+constexpr T radians(T degrees)
 {
 	return degrees * (static_cast<T>(MATH_PI) / static_cast<T>(180));
 }
 
 template<typename T>
-constexpr T degrees(const T radians)
+constexpr T degrees(T radians)
 {
 	return radians * (static_cast<T>(180) / static_cast<T>(MATH_PI));
 }
 
-/** Save way to check if float is zero */
-inline bool isZero(const float val)
+/** Safe way to check if float is zero */
+inline bool isZero(float val)
 {
 	return fabsf(val - 0.0f) < FLT_EPSILON;
 }
 
-/** Save way to check if double is zero */
-inline bool isZero(const double val)
+/** Safe way to check if double is zero */
+inline bool isZero(double val)
 {
 	return fabs(val - 0.0) < DBL_EPSILON;
 }