diff --git a/fuzz/get_all_corpora b/fuzz/get_all_corpora
index 87c5b4de..471c7671 100755
--- a/fuzz/get_all_corpora
+++ b/fuzz/get_all_corpora
@@ -1,6 +1,6 @@
 #!/bin/sh -eu
 
-if ! grep -q FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION Makefile; then
+if ! grep FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION Makefile >/dev/null; then
   echo "The fuzzers haven't been built for fuzzing (maybe for regression testing !?)"
   echo "Please built regarding README.md and try again."
   exit 1
diff --git a/fuzz/get_ossfuzz_corpora b/fuzz/get_ossfuzz_corpora
index bab7079e..e53d0d67 100755
--- a/fuzz/get_ossfuzz_corpora
+++ b/fuzz/get_ossfuzz_corpora
@@ -13,7 +13,7 @@ if test -z "$1"; then
   exit 1
 fi
 
-if ! grep -q FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION Makefile; then
+if ! grep FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION Makefile >/dev/null; then
   echo "The fuzzers haven't been built for fuzzing (maybe for regression testing !?)"
   echo "Please built regarding README.md and try again."
   exit 1
diff --git a/fuzz/run-afl.sh b/fuzz/run-afl.sh
index 1e1af0f3..217afe26 100755
--- a/fuzz/run-afl.sh
+++ b/fuzz/run-afl.sh
@@ -17,7 +17,7 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with GNU Wget.  If not, see <https://www.gnu.org/licenses/>.
 
-if ! grep -q '^CC=.afl-clang-fast' ../config.log; then
+if ! grep '^CC=.afl-clang-fast' ../config.log >/dev/null; then
 	echo "compile first library as:"
 	echo "CC=afl-clang-fast ./configure"
 	exit 1
diff --git a/fuzz/run-clang.sh b/fuzz/run-clang.sh
index 2f307a1d..40f2a15b 100755
--- a/fuzz/run-clang.sh
+++ b/fuzz/run-clang.sh
@@ -30,7 +30,7 @@ if test -z "$1"; then
 	exit 1
 fi
 
-if ! grep -q FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION Makefile; then
+if ! grep FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION Makefile >/dev/null; then
   echo "The fuzzers haven't been built for fuzzing (maybe for regression testing !?)"
   echo "Please built regarding README.md and try again."
   exit 1