diff -ur yoshimi-1.5.1/src/CMakeLists.txt yoshimi-1.5.1.new/src/CMakeLists.txt
--- yoshimi-1.5.1/src/CMakeLists.txt	2017-03-30 13:57:26.000000000 +0100
+++ yoshimi-1.5.1.new/src/CMakeLists.txt	2017-04-09 19:47:52.797194278 +0100
@@ -41,6 +41,7 @@
     # relative paths break some scripts(?)
 set (CMAKE_SKIP_RULE_DEPENDENCY OFF)
     # Rebuild objects if rules have changed, even if source hasn't.
+set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
 
 message (STATUS "Building Yoshimi version ${YOSHIMI_VERSION} for ${CMAKE_SYSTEM_NAME}")
 
@@ -82,12 +83,12 @@
 option (ShowNoteOnTimes "Report Note-On Times" OFF)
 
 set (BuildOptions_x86_64AMD
-    "-O3 -march=athlon64 -m64 -Wall -ffast-math -fno-finite-math-only -fomit-frame-pointer"
+  ${CMAKE_C_FLAGS}
   CACHE STRING "X86_64 compiler options"
 )
 
 set (BuildOptions_X86_64Core2
-    "-O3 -march=core2 -m64 -Wall -ffast-math -fno-finite-math-only -fomit-frame-pointer"
+  ${CMAKE_C_FLAGS}
   CACHE STRING "X86_64 compiler options"
 )
 
@@ -102,7 +103,7 @@
 )
 
 set (BuildOptionsBasic
-    "-O3 -msse -msse2 -mfpmath=sse -ffast-math -fomit-frame-pointer"
+    ${CMAKE_C_FLAGS}
     CACHE STRING "basic X86 complier options"
 )