diff --git a/Makefile.x86_64 b/Makefile.x86_64
index d23645058..99364752f 100644
--- a/Makefile.x86_64
+++ b/Makefile.x86_64
@@ -31,7 +31,7 @@ ifndef NO_AVX2
 ifeq ($(C_COMPILER), GCC)
 CCOMMON_OPT += -mavx2
 endif
-ifeq $(F_COMPILER), GFORTRAN)
+ifeq ($(F_COMPILER), GFORTRAN)
 FCOMMON_OPT += -mavx2
 endif
 endif