diff --git a/emitterc.go b/emitterc.go
index 0f47c9ca..0abf4418 100644
--- a/emitterc.go
+++ b/emitterc.go
@@ -1943,11 +1943,11 @@ func yaml_emitter_write_folded_scalar(emitter *yaml_emitter_t, value []byte) boo
 	for i := 0; i < len(value); {
 		if is_break(value, i) {
 			if !breaks && !leading_spaces && value[i] == '\n' {
-				k := 0
-				for is_break(value, k) {
+				k := i
+				for k < len(value) && is_break(value, k) {
 					k += width(value[k])
 				}
-				if !is_blankz(value, k) {
+				if k < len(value) && !is_blankz(value, k) {
 					if !put_break(emitter) {
 						return false
 					}
diff --git a/encode_test.go b/encode_test.go
index 4a8bf2e2..fba70d35 100644
--- a/encode_test.go
+++ b/encode_test.go
@@ -456,6 +456,24 @@ var marshalTests = []struct {
 			Style: yaml.SingleQuotedStyle,
 		},
 		"'foo'\n",
+	}, {
+		yaml.Node{
+			Kind:  yaml.ScalarNode,
+			Tag:   "!!str",
+			Style: yaml.FoldedStyle,
+			Value: `first line
+  more`,
+		},
+		">-\n    first line\n      more\n",
+	}, {
+		yaml.Node{
+			Kind:  yaml.ScalarNode,
+			Tag:   "!!str",
+			Style: yaml.FoldedStyle,
+			Value: `first line
+more`,
+		},
+		">-\n    first line\n\n    more\n",
 	},
 
 	// Enforced tagging with shorthand notation (issue #616).