diff --git a/util.go b/util.go
index a837d09..e89205f 100644
--- a/util.go
+++ b/util.go
@@ -57,8 +57,9 @@ func fixModes(modes map[string]string) modeMap {
 		"atmospheric":   ModeTypeProduct}
 
 	for name := range fixedModes {
-		value, _ := modes[name]
-		fixedModes[name] = strToModeType(value)
+		if value, ok := modes[name]; ok {
+			fixedModes[name] = strToModeType(value)
+		}
 	}
 
 	return fixedModes