diff --git a/makefile.mingw b/makefile.mingw
index 0213358..4e0d1ce 100644
--- a/makefile.mingw
+++ b/makefile.mingw
@@ -25,7 +25,7 @@ CFLAGS    = -O2 -DUSE_LTM -DLTM_DESC -I../libtommath
 EXTRALIBS = -L../libtommath -ltommath
 
 #Compilation flags
-LTC_CFLAGS  = $(CFLAGS) -Isrc/headers -Itests -DLTC_SOURCE
+LTC_CFLAGS  = -Isrc/headers -Itests -DLTC_SOURCE $(CFLAGS)
 LTC_LDFLAGS = $(LDFLAGS) $(EXTRALIBS)
 VERSION=1.18.0-rc1
 
diff --git a/makefile.msvc b/makefile.msvc
index be1988a..de7e899 100644
--- a/makefile.msvc
+++ b/makefile.msvc
@@ -20,7 +20,7 @@ CFLAGS    = /Ox /DUSE_LTM /DLTM_DESC /I../libtommath
 EXTRALIBS = ../libtommath/tommath.lib
 
 #Compilation flags
-LTC_CFLAGS  = $(CFLAGS) /nologo /Isrc/headers/ /Itests/ /D_CRT_SECURE_NO_WARNINGS /D_CRT_NONSTDC_NO_DEPRECATE /DLTC_SOURCE /W3
+LTC_CFLAGS  = /nologo /Isrc/headers/ /Itests/ /D_CRT_SECURE_NO_WARNINGS /D_CRT_NONSTDC_NO_DEPRECATE /DLTC_SOURCE /W3 $(CFLAGS)
 LTC_LDFLAGS = advapi32.lib $(EXTRALIBS)
 VERSION=1.18.0-rc1
 
diff --git a/makefile.unix b/makefile.unix
index 39722e8..8c437ad 100644
--- a/makefile.unix
+++ b/makefile.unix
@@ -37,7 +37,7 @@ CFLAGS    = -O2 -DUSE_LTM -DLTM_DESC -I../libtommath
 EXTRALIBS = ../libtommath/libtommath.a
 
 #Compilation flags
-LTC_CFLAGS  = $(CFLAGS) -Isrc/headers -Itests -DLTC_SOURCE
+LTC_CFLAGS  = -Isrc/headers -Itests -DLTC_SOURCE $(CFLAGS)
 LTC_LDFLAGS = $(LDFLAGS) $(EXTRALIBS)
 VERSION=1.18.0-rc1