diff --git a/external-packages/INLAspacetime/build/Makefile.win b/external-packages/INLAspacetime/build/Makefile.win
index 0c5ee3099..79fbb9335 100644
--- a/external-packages/INLAspacetime/build/Makefile.win
+++ b/external-packages/INLAspacetime/build/Makefile.win
@@ -1,4 +1,4 @@
-CFLAGS = $(FLAGS) -O2 -mtune=generic -fopenmp  -fpic -I.
+CFLAGS = $(FLAGS) -O3 -mtune=generic -fopenmp  -fpic -I.
 LDFLAGS = 
 TARGET = libINLAspacetime.so
 OBJ = $(patsubst %.c,%.o,$(wildcard *.c))
diff --git a/external-packages/fbesag/build/Makefile.win b/external-packages/fbesag/build/Makefile.win
index cee018695..0562d800f 100644
--- a/external-packages/fbesag/build/Makefile.win
+++ b/external-packages/fbesag/build/Makefile.win
@@ -1,4 +1,4 @@
-CFLAGS = $(FLAGS) -O2 -mtune=generic -fopenmp  -fpic -I.
+CFLAGS = $(FLAGS) -O3 -mtune=generic -fopenmp  -fpic -I.
 LDFLAGS = 
 TARGET = libfbesag.so
 OBJ = $(patsubst %.c,%.o,$(wildcard *.c))
diff --git a/external-packages/rSPDE/build/Makefile.win b/external-packages/rSPDE/build/Makefile.win
index 3abf354a0..c90242bd7 100644
--- a/external-packages/rSPDE/build/Makefile.win
+++ b/external-packages/rSPDE/build/Makefile.win
@@ -1,5 +1,5 @@
-CFLAGS = $(FLAGS) -O2 -mtune=generic -fopenmp  -fpic -I.
-CXXFLAGS = $(FLAGS) -O2 -mtune=generic -fopenmp  -fpic -I. -I$(EIGEN)
+CFLAGS = $(FLAGS) -O3 -mtune=generic -fopenmp  -fpic -I.
+CXXFLAGS = $(FLAGS) -O3 -mtune=generic -fopenmp  -fpic -I. -I$(EIGEN)
 LDFLAGS = 
 TARGET = librSPDE.so
 OBJ = $(patsubst %.c,%.o,$(wildcard *.c)) $(patsubst %.cpp,%.o,$(wildcard *.cpp))