diff --git a/acinclude.m4 b/acinclude.m4
index 26b90c21f..8012688b1 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -605,7 +605,7 @@ for be in ${BACKENDS}; do
 
     gphoto2)
     if test "${HAVE_GPHOTO2}" != "true" \
-      -o "${sane_cv_use_libjpeg}" != "yes"; then
+      || test "${sane_cv_use_libjpeg}" != "yes"; then
       echo "*** $be backend requires gphoto2 and JPEG libraries - $DISABLE_MSG"
       backend_supported="no"
     fi
diff --git a/configure.ac b/configure.ac
index 5d3a95fb1..d2f9e6886 100644
--- a/configure.ac
+++ b/configure.ac
@@ -180,7 +180,7 @@ else
 	fi
 fi
 
-if test "$with_snmp" = "yes" -a "${LIBSNMP_EXISTS}x" = "yesx"; then
+if test "$with_snmp" = "yes" && test "${LIBSNMP_EXISTS}x" = "yesx"; then
 	AC_SUBST(SNMP_LIBS)
 	AC_SUBST(SNMP_CFLAGS)
 	AC_DEFINE(HAVE_LIBSNMP, 1, [Define to 1 if you have the net-snmp library.])