diff --git a/amplifiers/elecraft/kpa.c b/amplifiers/elecraft/kpa.c
index 8ffbbe28e..b7bf05a05 100644
--- a/amplifiers/elecraft/kpa.c
+++ b/amplifiers/elecraft/kpa.c
@@ -90,7 +90,7 @@ int kpa_close(AMP *amp)
     return RIG_OK;
 }
 
-int kpa_flushbuffer(AMP *amp)
+static int kpa_flushbuffer(AMP *amp)
 {
     rig_debug(RIG_DEBUG_VERBOSE, "%s called\n", __func__);
 
diff --git a/include/hamlib/rig.h b/include/hamlib/rig.h
index f165dca29..814eb2921 100644
--- a/include/hamlib/rig.h
+++ b/include/hamlib/rig.h
@@ -3888,7 +3888,7 @@ locator2longlat HAMLIB_PARAMS((double *longitude,
                                double *latitude,
                                const char *locator));
 
-extern HAMLIB_EXPORT(char*) rig_make_md5(char *pass);
+extern HAMLIB_EXPORT(char*) rig_make_md5(const char *pass);
 
 extern HAMLIB_EXPORT(int) rig_set_lock_mode(RIG *rig, int lock);
 extern HAMLIB_EXPORT(int) rig_get_lock_mode(RIG *rig, int *lock);
diff --git a/rigs/kenwood/xg3.c b/rigs/kenwood/xg3.c
index 271bebca2..de65d8282 100644
--- a/rigs/kenwood/xg3.c
+++ b/rigs/kenwood/xg3.c
@@ -75,22 +75,22 @@ static struct kenwood_priv_caps xg3_priv_caps =
 
 
 /* XG3 specific rig_caps API function declarations */
-int xg3_init(RIG *rig);
-int xg3_open(RIG *rig);
-int xg3_set_vfo(RIG *rig, vfo_t vfo);
-int xg3_get_vfo(RIG *rig, vfo_t *vfo);
-int xg3_set_freq(RIG *rig, vfo_t vfo, freq_t freq);
-int xg3_get_freq(RIG *rig, vfo_t vfo, freq_t *freq);
-int xg3_get_ptt(RIG *rig, vfo_t vfo, ptt_t *ptt);
-int xg3_set_ptt(RIG *rig, vfo_t vfo, ptt_t ptt);
-int xg3_set_level(RIG *rig, vfo_t vfo, setting_t level, value_t val);
-int xg3_get_level(RIG *rig, vfo_t vfo, setting_t level, value_t *val);
-int xg3_set_powerstat(RIG *rig, powerstat_t status);
-int xg3_get_powerstat(RIG *rig, powerstat_t *status);
-int xg3_set_mem(RIG *rig, vfo_t vfo, int ch);
-int xg3_get_mem(RIG *rig, vfo_t vfo, int *ch);
-int xg3_set_parm(RIG *rig, setting_t parm, value_t val);
-int xg3_get_parm(RIG *rig, setting_t parm, value_t *val);
+static int xg3_init(RIG *rig);
+static int xg3_open(RIG *rig);
+static int xg3_set_vfo(RIG *rig, vfo_t vfo);
+static int xg3_get_vfo(RIG *rig, vfo_t *vfo);
+static int xg3_set_freq(RIG *rig, vfo_t vfo, freq_t freq);
+static int xg3_get_freq(RIG *rig, vfo_t vfo, freq_t *freq);
+static int xg3_get_ptt(RIG *rig, vfo_t vfo, ptt_t *ptt);
+static int xg3_set_ptt(RIG *rig, vfo_t vfo, ptt_t ptt);
+static int xg3_set_level(RIG *rig, vfo_t vfo, setting_t level, value_t val);
+static int xg3_get_level(RIG *rig, vfo_t vfo, setting_t level, value_t *val);
+static int xg3_set_powerstat(RIG *rig, powerstat_t status);
+static int xg3_get_powerstat(RIG *rig, powerstat_t *status);
+static int xg3_set_mem(RIG *rig, vfo_t vfo, int ch);
+static int xg3_get_mem(RIG *rig, vfo_t vfo, int *ch);
+static int xg3_set_parm(RIG *rig, setting_t parm, value_t val);
+static int xg3_get_parm(RIG *rig, setting_t parm, value_t *val);
 
 
 /*
@@ -183,7 +183,7 @@ struct rig_caps xg3_caps =
 /*
  * xg3_init()
  */
-int xg3_init(RIG *rig)
+static int xg3_init(RIG *rig)
 {
     struct kenwood_priv_data *priv;
     int i;
@@ -225,7 +225,7 @@ int xg3_init(RIG *rig)
 /*
  * xg3_open()
  */
-int xg3_open(RIG *rig)
+static int xg3_open(RIG *rig)
 {
     int err;
     ptt_t ptt;
@@ -245,7 +245,7 @@ int xg3_open(RIG *rig)
 }
 
 
-int xg3_set_level(RIG *rig, vfo_t vfo, setting_t level, value_t val)
+static int xg3_set_level(RIG *rig, vfo_t vfo, setting_t level, value_t val)
 {
     char levelbuf[16];
 
@@ -275,7 +275,7 @@ int xg3_set_level(RIG *rig, vfo_t vfo, setting_t level, value_t val)
 /*
  * kenwood_get_level
  */
-int xg3_get_level(RIG *rig, vfo_t vfo, setting_t level, value_t *val)
+static int xg3_get_level(RIG *rig, vfo_t vfo, setting_t level, value_t *val)
 {
     char cmdbuf[32], replybuf[32];
     int retval;
@@ -343,7 +343,7 @@ int xg3_get_level(RIG *rig, vfo_t vfo, setting_t level, value_t *val)
 /*
  * xg3_get_vfo
  */
-int xg3_get_vfo(RIG *rig, vfo_t *vfo)
+static int xg3_get_vfo(RIG *rig, vfo_t *vfo)
 {
     rig_debug(RIG_DEBUG_VERBOSE, "%s called\n", __func__);
 
@@ -359,7 +359,7 @@ int xg3_get_vfo(RIG *rig, vfo_t *vfo)
 /*
  * xg3_set_vfo
  */
-int xg3_set_vfo(RIG *rig, vfo_t vfo)
+static int xg3_set_vfo(RIG *rig, vfo_t vfo)
 {
     rig_debug(RIG_DEBUG_VERBOSE, "%s called\n", __func__);
 
@@ -379,7 +379,7 @@ int xg3_set_vfo(RIG *rig, vfo_t vfo)
 /*
  * xg3_set_freq
  */
-int xg3_set_freq(RIG *rig, vfo_t vfo, freq_t freq)
+static int xg3_set_freq(RIG *rig, vfo_t vfo, freq_t freq)
 {
     int err;
     vfo_t tvfo;
@@ -422,7 +422,7 @@ int xg3_set_freq(RIG *rig, vfo_t vfo, freq_t freq)
 /*
  * xg3_get_freq
  */
-int xg3_get_freq(RIG *rig, vfo_t vfo, freq_t *freq)
+static int xg3_get_freq(RIG *rig, vfo_t vfo, freq_t *freq)
 {
     struct hamlib_port *rp;
     char freqbuf[50];
@@ -494,7 +494,7 @@ int xg3_get_freq(RIG *rig, vfo_t vfo, freq_t *freq)
 /*
  * xg3_set_powerstat
  */
-int xg3_set_powerstat(RIG *rig, powerstat_t status)
+static int xg3_set_powerstat(RIG *rig, powerstat_t status)
 {
     rig_debug(RIG_DEBUG_VERBOSE, "%s called\n", __func__);
 
@@ -514,7 +514,7 @@ int xg3_set_powerstat(RIG *rig, powerstat_t status)
 /*
  * xg3_get_powerstat
  */
-int xg3_get_powerstat(RIG *rig, powerstat_t *status)
+static int xg3_get_powerstat(RIG *rig, powerstat_t *status)
 {
     const char *cmd = "G";      // any command to test will do
     char buf[6];
@@ -540,7 +540,7 @@ int xg3_get_powerstat(RIG *rig, powerstat_t *status)
 /*
  * xg3_set_mem
  */
-int xg3_set_mem(RIG *rig, vfo_t vfo, int ch)
+static int xg3_set_mem(RIG *rig, vfo_t vfo, int ch)
 {
     char cmdbuf[32];
     int retval;
@@ -569,7 +569,7 @@ int xg3_set_mem(RIG *rig, vfo_t vfo, int ch)
 /*
  * xg3_get_mem
  */
-int xg3_get_mem(RIG *rig, vfo_t vfo, int *ch)
+static int xg3_get_mem(RIG *rig, vfo_t vfo, int *ch)
 {
     char cmdbuf[32];
     char reply[32];
@@ -602,7 +602,7 @@ int xg3_get_mem(RIG *rig, vfo_t vfo, int *ch)
 /*
  * xg3_set_ptt
  */
-int xg3_set_ptt(RIG *rig, vfo_t vfo, ptt_t ptt)
+static int xg3_set_ptt(RIG *rig, vfo_t vfo, ptt_t ptt)
 {
     int retval;
 
@@ -622,7 +622,7 @@ int xg3_set_ptt(RIG *rig, vfo_t vfo, ptt_t ptt)
 /*
  * kenwood_get_ptt
  */
-int xg3_get_ptt(RIG *rig, vfo_t vfo, ptt_t *ptt)
+static int xg3_get_ptt(RIG *rig, vfo_t vfo, ptt_t *ptt)
 {
     char pttbuf[6];
     int retval;
@@ -650,7 +650,7 @@ int xg3_get_ptt(RIG *rig, vfo_t vfo, ptt_t *ptt)
 /*
  * xg3_set_parm
  */
-int xg3_set_parm(RIG *rig, setting_t parm, value_t val)
+static int xg3_set_parm(RIG *rig, setting_t parm, value_t val)
 {
     int ival;
     char cmdbuf[16];
@@ -679,7 +679,7 @@ int xg3_set_parm(RIG *rig, setting_t parm, value_t val)
 /*
  * xg3_get_parm
  */
-int xg3_get_parm(RIG *rig, setting_t parm, value_t *val)
+static int xg3_get_parm(RIG *rig, setting_t parm, value_t *val)
 {
     int ival;
     char replybuf[6];
diff --git a/rigs/tentec/jupiter.c b/rigs/tentec/jupiter.c
index 3a28dc677..ed9bcf8f6 100644
--- a/rigs/tentec/jupiter.c
+++ b/rigs/tentec/jupiter.c
@@ -257,7 +257,7 @@ static int tt538_transaction(RIG *rig, const char *cmd, int cmd_len,
 
     retval = tentec_transaction(rig, cmd, cmd_len, data, data_len);
 
-    if (data == NULL || (data != NULL && data_len > 0))
+    if (data == NULL || data_len > 0)
     {
         return retval;
     }
diff --git a/security/aes.c b/security/aes.c
index a46bdfdb4..9333b8a04 100644
--- a/security/aes.c
+++ b/security/aes.c
@@ -434,7 +434,7 @@ uint32 KT3[256];
 
 /* AES key scheduling routine */
 
-int aes_set_key(aes_context *ctx, uint8 *key, int nbits)
+int aes_set_key(aes_context *ctx, const uint8 *key, int nbits)
 {
     int i;
     uint32 *RK, *SK;
@@ -591,7 +591,7 @@ int aes_set_key(aes_context *ctx, uint8 *key, int nbits)
 
 /* AES 128-bit block encryption routine */
 
-void aes_encrypt(aes_context *ctx, uint8 input[16], uint8 output[16])
+void aes_encrypt(aes_context *ctx, const uint8 input[16], uint8 output[16])
 {
     uint32 *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;
 
@@ -681,7 +681,7 @@ void aes_encrypt(aes_context *ctx, uint8 input[16], uint8 output[16])
 
 /* AES 128-bit block decryption routine */
 
-void aes_decrypt(aes_context *ctx, uint8 input[16], uint8 output[16])
+void aes_decrypt(aes_context *ctx, const uint8 input[16], uint8 output[16])
 {
     uint32 *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;
 
diff --git a/security/aes.h b/security/aes.h
index 7c39f9eed..8b960ac3f 100755
--- a/security/aes.h
+++ b/security/aes.h
@@ -17,8 +17,8 @@ typedef struct
 }
 aes_context;
 
-int  aes_set_key( aes_context *ctx, uint8 *key, int nbits );
-void aes_encrypt( aes_context *ctx, uint8 input[16], uint8 output[16] );
-void aes_decrypt( aes_context *ctx, uint8 input[16], uint8 output[16] );
+int  aes_set_key( aes_context *ctx, const uint8 *key, int nbits );
+void aes_encrypt( aes_context *ctx, const uint8 input[16], uint8 output[16] );
+void aes_decrypt( aes_context *ctx, const uint8 input[16], uint8 output[16] );
 
 #endif /* aes.h */
diff --git a/security/md5.c b/security/md5.c
index b5ceb3883..9baf0a048 100644
--- a/security/md5.c
+++ b/security/md5.c
@@ -292,7 +292,7 @@ unsigned char *make_hash(const char *arg)
     return digest;
 }
 
-char *rig_make_md5(char *pass)
+char *rig_make_md5(const char *pass)
 {
     const unsigned char *hash = make_hash(pass);
     char *md5str = make_digest(hash, 16);
diff --git a/security/sha256.c b/security/sha256.c
index 73224a3e9..811cee623 100644
--- a/security/sha256.c
+++ b/security/sha256.c
@@ -53,7 +53,7 @@ void sha256_starts(sha256_context *ctx)
     ctx->state[7] = 0x5BE0CD19;
 }
 
-void sha256_process(sha256_context *ctx, uint8 data[64])
+void sha256_process(sha256_context *ctx, const uint8 data[64])
 {
     uint32 temp1, temp2, W[64];
     uint32 A, B, C, D, E, F, G, H;