diff --git a/sdrbase/dsp/cwkeyer.h b/sdrbase/dsp/cwkeyer.h
index a7d580964..a1c977a0c 100644
--- a/sdrbase/dsp/cwkeyer.h
+++ b/sdrbase/dsp/cwkeyer.h
@@ -127,7 +127,7 @@ private:
     bool m_dot;
     bool m_dash;
     bool m_elementOn;
-    char m_asciiChar;
+    signed char m_asciiChar;
     CWKeyIambicState m_keyIambicState;
     CWTextState m_textState;
     CWSmoother m_cwSmoother;