diff --git a/bin/ruby-build b/bin/ruby-build
index b26ae51f47..8851a69bd9 100755
--- a/bin/ruby-build
+++ b/bin/ruby-build
@@ -313,12 +313,12 @@ http() {
 }
 
 http_head_aria2c() {
-  aria2c --dry-run ${ARIA2_OPTS} "$1" >&4 2>&1
+  aria2c --dry-run --no-conf=true ${ARIA2_OPTS} "$1" >&4 2>&1
 }
 
 http_get_aria2c() {
   local out="${2:-$(mktemp "out.XXXXXX")}"
-  if aria2c --allow-overwrite=true -o "${out}" ${ARIA2_OPTS} "$1" >&4; then
+  if aria2c --allow-overwrite=true --no-conf=true -o "${out}" ${ARIA2_OPTS} "$1" >&4; then
     [ -n "$2" ] || cat "${out}"
   else
     false
diff --git a/test/fetch.bats b/test/fetch.bats
index 5286712df9..0bc450a8bc 100644
--- a/test/fetch.bats
+++ b/test/fetch.bats
@@ -21,7 +21,7 @@ setup() {
 }
 
 @test "using aria2c if available" {
-  stub aria2c "* -o * http://example.com/* : cp $FIXTURE_ROOT/\${4##*/} \$3"
+  stub aria2c "--allow-overwrite=true --no-conf=true -o * http://example.com/* : cp $FIXTURE_ROOT/\${5##*/} \$4"
 
   install_fixture definitions/without-checksum
   assert_success