diff --git a/src/openlibm/CMakeLists.txt b/src/openlibm/CMakeLists.txt
index 81045e2..d524879 100755
--- a/src/openlibm/CMakeLists.txt
+++ b/src/openlibm/CMakeLists.txt
@@ -37,7 +37,7 @@ endif()
 list(APPEND C_ASM_COMPILE_FLAGS "-ffp-contract=off" "-fno-fast-math" "-fno-rounding-math" "-fno-math-errno")
 list(APPEND C_ASM_COMPILE_FLAGS "-fPIC" "-std=c99" "-fno-builtin")
 list(APPEND C_ASM_COMPILE_FLAGS "-Wall" "-Wno-implicit-function-declaration")
-list(APPEND C_ASM_COMPILE_FLAGS "-DASSEMBLER" "-D__BSD_VISIBLE" "-O3")
+list(APPEND C_ASM_COMPILE_FLAGS "-DASSEMBLER" "-D__BSD_VISIBLE" "-O0 --mno-red-zone --mno-mmx")
 
 # Compiler-specific compile flags
 if("${CMAKE_C_COMPILER_ID}" MATCHES "Clang")
diff --git a/src/openlibm/Make.inc b/src/openlibm/Make.inc
index 7914e82..af8e1c7 100644
--- a/src/openlibm/Make.inc
+++ b/src/openlibm/Make.inc
@@ -106,7 +106,7 @@ endif
 
 # If CFLAGS does not contain a -O optimization flag, default to -O3
 ifeq ($(findstring -O,$(CFLAGS)),)
-CFLAGS_add += -O3
+CFLAGS_add += -O0 -mno-red-zone -mno-mmx
 endif
 
 ifneq (,$(findstring MINGW,$(OS)))