diff --git a/include/freerdp/assistance.h b/include/freerdp/assistance.h
index c8f5e62be..d41fef433 100644
--- a/include/freerdp/assistance.h
+++ b/include/freerdp/assistance.h
@@ -29,8 +29,8 @@ typedef struct rdp_assistance_file rdpAssistanceFile;
 extern "C" {
 #endif
 
-FREERDP_API BYTE* freerdp_assistance_hex_string_to_bin(const char* str, size_t* size);
-FREERDP_API char* freerdp_assistance_bin_to_hex_string(const BYTE* data, size_t size);
+FREERDP_API BYTE* freerdp_assistance_hex_string_to_bin(const void* str, size_t* size);
+FREERDP_API char* freerdp_assistance_bin_to_hex_string(const void* data, size_t size);
 
 FREERDP_API char* freerdp_assistance_generate_pass_stub(DWORD flags);
 FREERDP_API char* freerdp_assistance_construct_expert_blob(const char* name, const char* pass);
diff --git a/libfreerdp/common/assistance.c b/libfreerdp/common/assistance.c
index ce471683a..133de7034 100644
--- a/libfreerdp/common/assistance.c
+++ b/libfreerdp/common/assistance.c
@@ -664,11 +664,12 @@ fail:
 	return rc;
 }
 
-BYTE* freerdp_assistance_hex_string_to_bin(const char* str, size_t* size)
+BYTE* freerdp_assistance_hex_string_to_bin(const void* raw, size_t* size)
 {
 	size_t length;
 	BYTE* buffer;
 	size_t i;
+	const char* str = (const char*)raw;
 	length = strlen(str);
 
 	if ((length % 2) != 0)
@@ -710,11 +711,12 @@ BYTE* freerdp_assistance_hex_string_to_bin(const char* str, size_t* size)
 	return buffer;
 }
 
-char* freerdp_assistance_bin_to_hex_string(const BYTE* data, size_t size)
+char* freerdp_assistance_bin_to_hex_string(const void* raw, size_t size)
 {
 	size_t i;
 	char* p;
 	int ln, hn;
+	const char* data = (const char*)raw;
 	char bin2hex[] = "0123456789ABCDEF";
 	p = (char*) calloc((size + 1), 2);