diff --git a/client/cmdhf14a.h b/client/cmdhf14a.h
index 4a348a8f9..e80d00a2c 100644
--- a/client/cmdhf14a.h
+++ b/client/cmdhf14a.h
@@ -17,6 +17,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <ctype.h>
 #include "proxmark3.h"
 #include "common.h"
 #include "ui.h"
diff --git a/client/cmdlft55xx.h b/client/cmdlft55xx.h
index 1c0618532..41f7f1d4a 100644
--- a/client/cmdlft55xx.h
+++ b/client/cmdlft55xx.h
@@ -14,6 +14,7 @@
 #include <string.h>
 #include <inttypes.h>
 #include <time.h>
+#include <ctype.h>
 #include "proxmark3.h"
 #include "ui.h"
 #include "graph.h"
diff --git a/client/emv/cmdemv.h b/client/emv/cmdemv.h
index b94a0ea2a..1869eca14 100644
--- a/client/emv/cmdemv.h
+++ b/client/emv/cmdemv.h
@@ -15,6 +15,7 @@
 #include <stdlib.h>
 #include <inttypes.h>
 #include <string.h>
+#include <ctype.h>
 #include "proxmark3.h"
 #include "ui.h"
 #include "cmdparser.h"