diff --git a/src/afc.c b/src/afc.c
index d0f5cb7..fe99852 100644
--- a/src/afc.c
+++ b/src/afc.c
@@ -355,7 +355,7 @@
 /**
  * Returns counts of null characters within a string.
  */
-static uint32_t count_nullspaces(char *string, uint32_t number)
+static uint32_t count_nullspaces(const char *string, uint32_t number)
 {
 	uint32_t i = 0, nulls = 0;
 
diff --git a/tools/ideviceprovision.c b/tools/ideviceprovision.c
index 1dee899..754b84d 100644
--- a/tools/ideviceprovision.c
+++ b/tools/ideviceprovision.c
@@ -106,7 +106,7 @@
 	}
 }
 
-static size_t asn1_item_get_size(unsigned char* p)
+static size_t asn1_item_get_size(const unsigned char* p)
 {
 	size_t res = 0;
 	char bsize = *(p+1);
diff --git a/tools/idevicesyslog.c b/tools/idevicesyslog.c
index 4eb1605..44dd5ba 100644
--- a/tools/idevicesyslog.c
+++ b/tools/idevicesyslog.c
@@ -119,7 +119,7 @@
 	}
 }
 
-static int find_char(char c, char** p, char* end)
+static int find_char(char c, char** p, const char* end)
 {
 	while ((**p != c) && (*p < end)) {
 		(*p)++;