diff --git a/src/ELMduino.cpp b/src/ELMduino.cpp
index f0f41b9..825b1ea 100644
--- a/src/ELMduino.cpp
+++ b/src/ELMduino.cpp
@@ -2689,7 +2689,7 @@ void ELM327::currentDTCCodes(const bool &isBlocking)
             // Each response line will start with "43" indicating it is a response to a Mode 03 request.
             // See p. 31 of ELM327 datasheet for details and lookup table of code types.
 
-            uint codesFound = strlen(payload) / 8; // Each code found returns 8 chars starting with "43"
+            uint8_t codesFound = strlen(payload) / 8; // Each code found returns 8 chars starting with "43"
             idx = strstr(payload, "43") + 4;       // Pointer to first DTC code digit (third char in the response)
 
             if (codesFound > DTC_MAX_CODES)        // I don't think the ELM is capable of returning
diff --git a/src/ELMduino.h b/src/ELMduino.h
index 4b9f8da..8040dc1 100644
--- a/src/ELMduino.h
+++ b/src/ELMduino.h
@@ -271,8 +271,8 @@ const int8_t ELM_TIMEOUT           = 7;
 const int8_t ELM_GETTING_MSG       = 8;
 const int8_t ELM_MSG_RXD           = 9;
 const int8_t ELM_GENERAL_ERROR     = -1;
-const int8_t DTC_CODE_LEN		   = 6;
-const int8_t DTC_MAX_CODES		   = 16;
+const uint8_t DTC_CODE_LEN		   = 6;
+const uint8_t DTC_MAX_CODES		   = 16;
 
 // Non-blocking (NB) command states
 typedef enum { SEND_COMMAND,
@@ -308,7 +308,7 @@ class ELM327
 	byte responseByte_7;
 
 	struct dtcResponse {
-		uint codesFound = 0;
+		uint8_t codesFound = 0;
 		char codes[DTC_MAX_CODES][DTC_CODE_LEN];
 	} DTC_Response;