diff --git a/src/signature.cpp b/src/signature.cpp
index c38c6d189c..b52bea4af1 100644
--- a/src/signature.cpp
+++ b/src/signature.cpp
@@ -54,7 +54,7 @@ static std::string CalculateHashV1(const std::string &filename)
 	fclose(f);
 
 	crypto_blake2b_final(&ctx, digest.data());
-	return FormatArrayAsHex(digest);
+	return FormatArrayAsHex(digest, true);
 }
 
 /**
@@ -87,7 +87,7 @@ static bool ValidateChecksum(const std::string &filename, const std::string &che
 		return false;
 	}
 	if (calculated_hash != hash) {
-		Debug(misc, 0, "Failed to validate signature: checksum mismatch for: {}", filename);
+		Debug(misc, 0, "Failed to validate signature: checksum mismatch for: {}, {}, {}", filename, calculated_hash, hash);
 		return false;
 	}
 
diff --git a/src/string.cpp b/src/string.cpp
index 36d0fecda3..c176546311 100644
--- a/src/string.cpp
+++ b/src/string.cpp
@@ -210,14 +210,18 @@ const char *str_fix_scc_encoded(char *str, const char *last)
  * @param data Array to format
  * @return Converted string.
  */
-std::string FormatArrayAsHex(std::span<const byte> data)
+std::string FormatArrayAsHex(std::span<const byte> data, bool upper_case)
 {
 	std::string hex_output;
 	hex_output.resize(data.size() * 2);
 
 	char txt[3];
 	for (uint i = 0; i < data.size(); ++i) {
-		seprintf(txt, lastof(txt), "%02x", data[i]);
+		if (upper_case) {
+			seprintf(txt, lastof(txt), "%02X", data[i]);
+		} else {
+			seprintf(txt, lastof(txt), "%02x", data[i]);
+		}
 		hex_output[i * 2] = txt[0];
 		hex_output[(i * 2) + 1] = txt[1];
 	}
diff --git a/src/string_func.h b/src/string_func.h
index 7c72b93eee..b50a192814 100644
--- a/src/string_func.h
+++ b/src/string_func.h
@@ -41,7 +41,7 @@ int CDECL vseprintf(char *str, const char *last, const char *format, va_list ap)
 std::string CDECL stdstr_fmt(const char *str, ...) WARN_FORMAT(1, 2);
 std::string stdstr_vfmt(const char *str, va_list va) WARN_FORMAT(1, 0);
 
-std::string FormatArrayAsHex(std::span<const byte> data);
+std::string FormatArrayAsHex(std::span<const byte> data, bool upper_case = false);
 
 char *StrMakeValidInPlace(char *str, const char *last, StringValidationSettings settings = SVS_REPLACE_WITH_QUESTION_MARK) NOACCESS(2);
 [[nodiscard]] std::string StrMakeValid(std::string_view str, StringValidationSettings settings = SVS_REPLACE_WITH_QUESTION_MARK);
diff --git a/src/survey.cpp b/src/survey.cpp
index 093d8da93b..246e393b98 100644
--- a/src/survey.cpp
+++ b/src/survey.cpp
@@ -324,7 +324,7 @@ void SurveyGrfs(nlohmann::json &survey)
 		auto grfid = fmt::format("{:08x}", BSWAP32(c->ident.grfid));
 		auto &grf = survey[grfid];
 
-		grf["md5sum"] = FormatArrayAsHex(c->ident.md5sum);
+		grf["md5sum"] = FormatArrayAsHex(c->ident.md5sum, true);
 		grf["status"] = c->status;
 
 		if ((c->palette & GRFP_GRF_MASK) == GRFP_GRF_UNSET) grf["palette"] = "unset";