diff --git a/armsrc/dbprint.c b/armsrc/dbprint.c
index 9b18b7aca..bfeb0ded2 100644
--- a/armsrc/dbprint.c
+++ b/armsrc/dbprint.c
@@ -22,7 +22,7 @@
 // Debug print functions, to go out over USB, to the usual PC-side client.
 //=============================================================================
 
-void DbpStringEx(uint32_t flags, char *src, size_t srclen) {
+void DbpStringEx(uint32_t flags, const char *src, size_t srclen) {
 #if DEBUG
     struct {
         uint16_t flag;
@@ -35,7 +35,7 @@ void DbpStringEx(uint32_t flags, char *src, size_t srclen) {
 #endif
 }
 
-void DbpString(char *str) {
+void DbpString(const char *str) {
 #if DEBUG
     DbpStringEx(FLAG_LOG, str, strlen(str));
 #endif
@@ -98,7 +98,7 @@ void Dbhexdump(int len, uint8_t *d, bool bAsci) {
 #endif
 }
 
-void print_result(char *name, uint8_t *buf, size_t len) {
+void print_result(const char *name, uint8_t *buf, size_t len) {
 
     uint8_t *p = buf;
     uint16_t tmp = len & 0xFFF0;
diff --git a/armsrc/dbprint.h b/armsrc/dbprint.h
index c3229f46f..2a8444ef3 100644
--- a/armsrc/dbprint.h
+++ b/armsrc/dbprint.h
@@ -42,12 +42,12 @@
         reply_via_usb = tmpusb;}
 
 
-void DbpString(char *str);
-void DbpStringEx(uint32_t flags, char *src, size_t srclen);
+void DbpString(const char *str);
+void DbpStringEx(uint32_t flags, const char *src, size_t srclen);
 void Dbprintf(const char *fmt, ...);
 void DbprintfEx(uint32_t flags, const char *fmt, ...);
 void Dbhexdump(int len, uint8_t *d, bool bAsci);
-void print_result(char *name, uint8_t *buf, size_t len);
+void print_result(const char *name, uint8_t *buf, size_t len);
 //void PrintToSendBuffer(void);
 
 #endif
diff --git a/armsrc/lfops.c b/armsrc/lfops.c
index e89e594d8..5c3e6973b 100644
--- a/armsrc/lfops.c
+++ b/armsrc/lfops.c
@@ -1535,7 +1535,7 @@ void CmdIOdemodFSK(int findone, uint32_t *high, uint32_t *low, int ledcontrol) {
         calccrc &= 0xff;
         calccrc = 0xff - calccrc;
 
-        char *crcStr = (crc == calccrc) ? "ok" : "!crc";
+        const char *crcStr = (crc == calccrc) ? "ok" : "!crc";
 
         Dbprintf("IO Prox XSF(%02d)%02x:%05d (%08x%08x)  [%02x %s]", version, facilitycode, number, code, code2, crc, crcStr);
         // if we're only looking for one tag