diff --git a/CMakeLists.txt b/CMakeLists.txt
index 478e1a2fcb6f94e2d28fe85671ccdee769f5f673..435773d7bcf9b7064062d3e0f5486e003182b55c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -57,6 +57,7 @@ if(UNIX)
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -m64")
   endif()
   # C compiler flags
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -ffp-contract=off")  # disable floating point operation contraction
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -pedantic -Wcast-qual -Wall -W -Wextra -Wno-long-long")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wpointer-arith -Wstrict-prototypes -Wmissing-prototypes")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror-implicit-function-declaration -Wno-unused-parameter")
diff --git a/Makefile b/Makefile
index 8955e04e665a5468618937419cf2118978436d21..811d38b6842ef13dfb82ad5a81a74102e014f7af 100644
--- a/Makefile
+++ b/Makefile
@@ -58,7 +58,7 @@ endif
 CFLAGS   += -std=c99 -pedantic -Wcast-qual -Wall -W -Wextra -Wno-long-long     \
             -Wpointer-arith -Wstrict-prototypes -Wmissing-prototypes  \
             -Werror-implicit-function-declaration \
-            -Wno-implicit-fallthrough
+            -Wno-implicit-fallthrough -ffp-contract=off
 
 # libs to link
 LDLIBS   += -lm