diff --git a/.travis.yml b/.travis.yml
index a269c4e..64ab75c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -163,6 +163,10 @@ matrix:
           packages:
             - clang-4.0
 
+    # Link time optimization
+    - env: SANITIZER=1 COMPILE_LTO=1 BUILDOPTIONS='--with-cc=gcc-5 --with-m64 --with-travis-valgrind'
+    - env: SANITIZER=1 COMPILE_LTO=1 BUILDOPTIONS='--with-cc=clang-7 --with-m64 --with-travis-valgrind'
+
     # GCC for the x86-64 architecture with restricted limb sizes
     # formerly started with the option "--with-low-mp" to testme.sh
     # but testing all three in one run took to long and timed out.
diff --git a/demo/shared.c b/demo/shared.c
index 5ada460..7ef4756 100644
--- a/demo/shared.c
+++ b/demo/shared.c
@@ -3,7 +3,7 @@
 void ndraw(const mp_int *a, const char *name)
 {
    char *buf;
-   size_t size;
+   size_t size = 0;
    mp_err err;
 
    if ((err = mp_radix_size(a, 10, &size)) != MP_OKAY) {
diff --git a/makefile b/makefile
index 4045390..a04cd4d 100644
--- a/makefile
+++ b/makefile
@@ -77,7 +77,7 @@ profiled_single: pre_gen
 	rm -f *.o timing
 	$(CC) $(LTM_CFLAGS) -fbranch-probabilities -c pre_gen/tommath_amalgam.c -o tommath_amalgam.o
 	$(AR) $(ARFLAGS) $(LIBNAME) tommath_amalgam.o
-	ranlib $(LIBNAME)
+	$(RANLIB) $(LIBNAME)
 
 install: $(LIBNAME)
 	install -d $(DESTDIR)$(LIBPATH)
diff --git a/makefile_include.mk b/makefile_include.mk
index 4b5961c..aebbc8f 100644
--- a/makefile_include.mk
+++ b/makefile_include.mk
@@ -86,6 +86,12 @@ LTM_CFLAGS += -O3 -funroll-loops
 LTM_CFLAGS  += -fomit-frame-pointer
 endif
 
+ifdef COMPILE_LTO
+LTM_CFLAGS += -flto
+AR = $(subst clang,llvm-ar,$(subst gcc,gcc-ar,$(CC)))
+RANLIB = $(subst clang,llvm-ranlib,$(subst gcc,gcc-ranlib,$(CC)))
+endif
+
 endif # COMPILE_SIZE
 
 ifneq ($(findstring clang,$(CC)),)
diff --git a/testme.sh b/testme.sh
index 6c71ac4..1a03f55 100755
--- a/testme.sh
+++ b/testme.sh
@@ -107,7 +107,7 @@ _make()
 {
   echo -ne " Compile $1 $2"
   suffix=$(echo ${1}${2}  | tr ' ' '_')
-  CC="$1" CFLAGS="$2 $TEST_CFLAGS" make -j$MAKE_JOBS $3 $MAKE_OPTIONS > /dev/null 2>gcc_errors_${suffix}.log
+  CC="$1" CFLAGS="$2 $TEST_CFLAGS" make -j$MAKE_JOBS $3 $MAKE_OPTIONS 2>gcc_errors_${suffix}.log
   errcnt=$(wc -l < gcc_errors_${suffix}.log)
   if [[ ${errcnt} -gt 1 ]]; then
     echo " failed"
@@ -354,7 +354,7 @@ _banner
 if [[ "$TEST_VS_MTEST" != "" ]]
 then
    make clean > /dev/null
-   _make "${compilers[0]} ${archflags[0]}" "$CFLAGS" "mtest_opponent"
+   _make "${compilers[0]}" "${archflags[0]} $CFLAGS" "mtest_opponent"
    echo
    _make "gcc" "$MTEST_RAND" "mtest"
    echo
@@ -394,15 +394,15 @@ do
     fi
     if [[ "$VALGRIND_BIN" != "" ]]
     then
-      _runvalgrind "$i $a" "$CFLAGS"
+      _runvalgrind "$i" "$a $CFLAGS"
       [ "$WITH_LOW_MP" != "1" ] && continue
-      _runvalgrind "$i $a" "-DMP_16BIT $CFLAGS"
-      _runvalgrind "$i $a" "-DMP_32BIT $CFLAGS"
+      _runvalgrind "$i" "$a -DMP_16BIT $CFLAGS"
+      _runvalgrind "$i" "$a -DMP_32BIT $CFLAGS"
     else
-      _runtest "$i $a" "$CFLAGS"
+      _runtest "$i" "$a $CFLAGS"
       [ "$WITH_LOW_MP" != "1" ] && continue
-      _runtest "$i $a" "-DMP_16BIT $CFLAGS"
-      _runtest "$i $a" "-DMP_32BIT $CFLAGS"
+      _runtest "$i" "$a -DMP_16BIT $CFLAGS"
+      _runtest "$i" "$a -DMP_32BIT $CFLAGS"
     fi
   done
 done