diff --git a/include/eible/ColumnType.h b/include/eible/ColumnType.h
index cd70cab..962b5fa 100644
--- a/include/eible/ColumnType.h
+++ b/include/eible/ColumnType.h
@@ -2,7 +2,7 @@
 
 #include <QMetaType>
 
-enum class ColumnType : char
+enum class ColumnType : signed char
 {
     UNKNOWN = -1,
     STRING,