diff --git a/decode_test.go b/decode_test.go
index 7e0e1101..51f50709 100644
--- a/decode_test.go
+++ b/decode_test.go
@@ -946,6 +946,7 @@ var unmarshalErrorTests = []struct {
 	{"{{.}}", `yaml: invalid map key: map\[string]interface \{\}\{".":interface \{\}\(nil\)\}`},
 	{"b: *a\na: &a {c: 1}", `yaml: unknown anchor 'a' referenced`},
 	{"%TAG !%79! tag:yaml.org,2002:\n---\nv: !%79!int '1'", "yaml: did not find expected whitespace"},
+	{"a:\n  1:\nb\n  2:", ".*could not find expected ':'"},
 	{
 		"a: &a [00,00,00,00,00,00,00,00,00]\n" +
 		"b: &b [*a,*a,*a,*a,*a,*a,*a,*a,*a]\n" +
diff --git a/scannerc.go b/scannerc.go
index 7c78d235..09673941 100644
--- a/scannerc.go
+++ b/scannerc.go
@@ -673,7 +673,9 @@ func yaml_parser_fetch_more_tokens(parser *yaml_parser_t) bool {
 				if simple_key.token_number < parser.tokens_parsed {
 					break
 				}
-				if yaml_simple_key_is_valid(parser, simple_key) && simple_key.token_number == parser.tokens_parsed {
+				if valid, ok := yaml_simple_key_is_valid(parser, simple_key); !ok {
+					return false
+				} else if valid && simple_key.token_number == parser.tokens_parsed {
 					need_more_tokens = true
 					break
 				}
@@ -886,9 +888,9 @@ func yaml_parser_fetch_next_token(parser *yaml_parser_t) (ok bool) {
 		"found character that cannot start any token")
 }
 
-func yaml_simple_key_is_valid(parser *yaml_parser_t, simple_key *yaml_simple_key_t) bool {
+func yaml_simple_key_is_valid(parser *yaml_parser_t, simple_key *yaml_simple_key_t) (valid, ok bool) {
 	if !simple_key.possible {
-		return false
+		return false, true
 	}
 
 	// The 1.2 specification says:
@@ -902,14 +904,14 @@ func yaml_simple_key_is_valid(parser *yaml_parser_t, simple_key *yaml_simple_key
 	if simple_key.mark.line < parser.mark.line || simple_key.mark.index+1024 < parser.mark.index {
 		// Check if the potential simple key to be removed is required.
 		if simple_key.required {
-			return yaml_parser_set_scanner_error(parser,
+			return false, yaml_parser_set_scanner_error(parser,
 				"while scanning a simple key", simple_key.mark,
 				"could not find expected ':'")
 		}
 		simple_key.possible = false
-		return false
+		return false, true
 	}
-	return true
+	return true, true
 }
 
 // Check if a simple key may start at the current position and add it if
@@ -1372,7 +1374,10 @@ func yaml_parser_fetch_value(parser *yaml_parser_t) bool {
 	simple_key := &parser.simple_keys[len(parser.simple_keys)-1]
 
 	// Have we found a simple key?
-	if yaml_simple_key_is_valid(parser, simple_key) {
+	if valid, ok := yaml_simple_key_is_valid(parser, simple_key); !ok {
+		return false
+
+	} else if valid {
 
 		// Create the KEY token and insert it into the queue.
 		token := yaml_token_t{