diff --git a/.travis.yml b/.travis.yml
index e1a88c40510a2..14f3cafe3cb08 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -31,9 +31,9 @@ env:
     - BIGNUM=no
     - BIGNUM=no       ENDOMORPHISM=yes RECOVERY=yes EXPERIMENTAL=yes SCHNORRSIG=yes
     - BIGNUM=no       STATICPRECOMPUTATION=no
-    - BUILD=distcheck CTIMETEST= BENCH=
+    - BUILD=distcheck CTIMETEST=no BENCH=no
     - CPPFLAGS=-DDETERMINISTIC
-    - CFLAGS=-O0 CTIMETEST=
+    - CFLAGS=-O0 CTIMETEST=no
     - ECMULTGENPRECISION=2
     - ECMULTGENPRECISION=8
     - VALGRIND=yes ENDOMORPHISM=yes BIGNUM=no ASM=x86_64 EXPERIMENTAL=yes ECDH=yes  RECOVERY=yes EXTRAFLAGS="--disable-openssl-tests" CPPFLAGS=-DVALGRIND BUILD=
diff --git a/contrib/travis.sh b/contrib/travis.sh
index 4859756e89192..891027b709f7a 100755
--- a/contrib/travis.sh
+++ b/contrib/travis.sh
@@ -24,16 +24,16 @@ if [ -n "$BUILD" ]
 then
     make -j2 "$BUILD"
 fi
-if [ -n "$VALGRIND" ]
+if [ "$VALGRIND" = "yes" ]
 then
     make -j2
     # the `--error-exitcode` is required to make the test fail if valgrind found errors, otherwise it'll return 0 (http://valgrind.org/docs/manual/manual-core.html)
     valgrind --error-exitcode=42 ./tests 16
     valgrind --error-exitcode=42 ./exhaustive_tests
 fi
-if [ -n "$BENCH" ]
+if [ "$BENCH" = "yes" ]
 then
-    if [ -n "$VALGRIND" ]
+    if [ "$VALGRIND" = "yes" ]
     then
         # Using the local `libtool` because on macOS the system's libtool has nothing to do with GNU libtool
         EXEC='./libtool --mode=execute valgrind --error-exitcode=42'
@@ -61,7 +61,7 @@ then
         $EXEC ./bench_schnorrsig >> bench.log 2>&1
     fi
 fi
-if [ -n "$CTIMETEST" ]
+if [ "$CTIMETEST" = "yes" ]
 then
     ./libtool --mode=execute valgrind --error-exitcode=42 ./valgrind_ctime_test > valgrind_ctime_test.log 2>&1
 fi