Index: source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
===================================================================
--- source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
+++ source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
@@ -815,7 +815,8 @@
         // checksum
         if (m_bytes[0] == '$' && total_length > 4) {
           for (size_t i = 0; !binary && i < total_length; ++i) {
-            if (isprint(m_bytes[i]) == 0 && isspace(m_bytes[i]) == 0) {
+            unsigned char c = m_bytes[i];
+            if (isprint(c) == 0 && isspace(c) == 0) {
               binary = true;
             }
           }