diff --git a/Common/Buffer.cpp b/Common/Buffer.cpp
index a7e02df8b0..74ec5b747d 100644
--- a/Common/Buffer.cpp
+++ b/Common/Buffer.cpp
@@ -136,7 +136,9 @@ bool Buffer::FlushToFile(const Path &filename, bool clear) {
 }
 
 void Buffer::PeekAll(std::string *dest) {
-	dest->resize(data_.size());
+	// resize() here would leave that many zero bytes in front of the appended data.
+	dest->clear();
+	dest->reserve(data_.size());
 	data_.iterate_blocks(([dest](const char *blockData, size_t blockSize) {
 		dest->append(blockData, blockSize);
 		return true;
diff --git a/Common/Log.cpp b/Common/Log.cpp
index 183a1721f7..f95bb7549c 100644
--- a/Common/Log.cpp
+++ b/Common/Log.cpp
@@ -136,8 +136,9 @@ bool HandleAssert(bool isDebugAssert, const char *function, const char *file, in
 		const char *threadName = GetCurrentThreadName();
 		OutputDebugStringA(formatted);
 		printf("%s\n", formatted);
-		static const std::string caption = isDebugAssert ? "Debug Assert" : "Critical Assert";
-		std::wstring wcaption = ConvertUTF8ToWString(caption + " " + (threadName ? threadName : "(unknown thread)"));
+		// Not static - it'd freeze at whatever the first assert in the session was.
+		const char *caption = isDebugAssert ? "Debug Assert" : "Critical Assert";
+		std::wstring wcaption = ConvertUTF8ToWString(std::string(caption) + " " + (threadName ? threadName : "(unknown thread)"));
 		switch (MessageBox(g_dialogParent, ConvertUTF8ToWString(text).c_str(), wcaption.c_str(), msgBoxStyle)) {
 		case IDYES:
 			return true;
diff --git a/Common/StringUtils.cpp b/Common/StringUtils.cpp
index 4bf4d1cdaa..23bb1626a3 100644
--- a/Common/StringUtils.cpp
+++ b/Common/StringUtils.cpp
@@ -86,7 +86,11 @@ long parseLong(std::string s) {
 }
 
 bool containsNoCase(std::string_view haystack, std::string_view needle) {
-	auto pred = [](char ch1, char ch2) { return std::toupper(ch1) == std::toupper(ch2); };
+	// toupper is UB for negative values other than EOF, and char is signed here - non-ASCII bytes
+	// reach this from e.g. ELF symbol names.
+	auto pred = [](char ch1, char ch2) {
+		return std::toupper((unsigned char)ch1) == std::toupper((unsigned char)ch2);
+	};
 	auto found = std::search(haystack.begin(), haystack.end(), needle.begin(), needle.end(), pred);
 	return found != haystack.end();
 }
diff --git a/Core/TiltEventProcessor.cpp b/Core/TiltEventProcessor.cpp
index ab093a578f..279fc6ff84 100644
--- a/Core/TiltEventProcessor.cpp
+++ b/Core/TiltEventProcessor.cpp
@@ -55,6 +55,13 @@ inline float ApplyDeadzoneAxis(float x, float deadzone) {
 
 inline void ApplyDeadzoneXY(float x, float y, float *adjustedX, float *adjustedY, float deadzone, bool circular) {
 	if (circular) {
+		if (deadzone >= 0.99f) {
+			// Same guard as ApplyDeadzoneAxis - without it the factor below divides by ~0.
+			*adjustedX = x;
+			*adjustedY = y;
+			return;
+		}
+
 		if (x == 0.0f && y == 0.0f) {
 			*adjustedX = 0.0f;
 			*adjustedY = 0.0f;