Call character checking function with unsigned char

See https://wiki.sei.cmu.edu/confluence/display/c/STR37-C.+Arguments+to+character-handling+functions+must+be+representable+as+an+unsigned+char

1 files changed, 1 insertions, 1 deletions

diff --git a/IncSet.c b/IncSet.c
index e9e28934..b9a1d92d 100644
--- a/IncSet.c
+++ b/IncSet.c
@@ -137,7 +137,7 @@ bool IncSet_handleKey(IncSet* this, int ch, Panel* panel, IncMode_GetPanelValue
       if (size == 0) return true;
       IncMode_find(mode, panel, getPanelValue, 1);
       doSearch = false;
-   } else if (ch < 255 && isprint((char)ch)) {
+   } else if (0 < ch && ch < 255 && isprint((unsigned char)ch)) {
       if (mode->index < INCMODE_MAX) {
          mode->buffer[mode->index] = ch;
          mode->index++;