diff --git a/Common/Data/Encoding/Utf8.cpp b/Common/Data/Encoding/Utf8.cpp
index d8531e49de..0374229e9c 100644
--- a/Common/Data/Encoding/Utf8.cpp
+++ b/Common/Data/Encoding/Utf8.cpp
@@ -322,6 +322,10 @@ void ConvertUTF8ToJavaModifiedUTF8(std::string *output, std::string_view input)
 			output[out_idx++] = (char)0x80;
 			i++;
 		} else if ((c & 0xF0) == 0xF0) { // 4-byte sequence (U+10000 to U+10FFFF)
+			if (i + 4 > input.length()) {
+				// Bad.
+				break;
+			}
 			// Decode the Unicode code point from the UTF-8 sequence
 			uint32_t code_point = ((input[i] & 0x07) << 18) |
 				((input[i + 1] & 0x3F) << 12) |
@@ -345,6 +349,9 @@ void ConvertUTF8ToJavaModifiedUTF8(std::string *output, std::string_view input)
 			} else if ((c & 0xF0) == 0xE0) {
 				utf8_len = 3; // 3-byte sequence
 			}
+			if (i + utf8_len > input.length()) {
+				break;
+			}
 			memcpy(output->data() + out_idx, input.data() + i, utf8_len);
 			out_idx += utf8_len;
 			i += utf8_len;
diff --git a/Common/Thread/Waitable.h b/Common/Thread/Waitable.h
index abda42fef9..52870edcf6 100644
--- a/Common/Thread/Waitable.h
+++ b/Common/Thread/Waitable.h
@@ -30,9 +30,9 @@ public:
 			return true;
 
 		uint32_t us = budget_s > 0 ? (uint32_t)(budget_s * 1000000.0) : 0;
-		if (us == 0)
+		if (us == 0) {
 			return false;
-
+		}
 		std::unique_lock<std::mutex> lock(mutex_);
 		return cond_.wait_for(lock, std::chrono::microseconds(us), [&] { return triggered_.load(); });
 	}
diff --git a/Common/UI/Screen.cpp b/Common/UI/Screen.cpp
index 20ee69b01d..6cb652c2a2 100644
--- a/Common/UI/Screen.cpp
+++ b/Common/UI/Screen.cpp
@@ -313,8 +313,10 @@ void ScreenManager::sendMessage(UIMessage message, const char *value) {
 
 	// NOTE: Changed this to send the message to all screens, instead of just the top one,
 	// to allow EmuScreen to receive messages from popup menus. Hope this didn't break anything..
-	for (auto &iter : stack_) {
-		iter.screen->sendMessage(message, value);
+	for (const auto &iter : stack_) {
+		if (iter.screen) {
+			iter.screen->sendMessage(message, value);
+		}
 	}
 }
 
diff --git a/Core/ControlMapper.cpp b/Core/ControlMapper.cpp
index f32a6faaa1..4730dbd8d3 100644
--- a/Core/ControlMapper.cpp
+++ b/Core/ControlMapper.cpp
@@ -160,7 +160,10 @@ void ControlMapper::SetCallbacks(
 }
 
 void ControlMapper::SetPSPAxis(int device, int stick, char axis, float value) {
-	int axisId = axis == 'X' ? 0 : 1;
+	const int axisId = axis == 'X' ? 0 : 1;
+	if (stick != 0 && stick != 1) {
+		return;
+	}
 
 	float position[2];
 	position[0] = history_[stick][0];
diff --git a/UI/JitCompareScreen.cpp b/UI/JitCompareScreen.cpp
index 03044dd729..1f9244ece0 100644
--- a/UI/JitCompareScreen.cpp
+++ b/UI/JitCompareScreen.cpp
@@ -9,6 +9,9 @@
 #include "Core/MIPS/JitCommon/JitState.h"
 
 JitCompareScreen::JitCompareScreen() : UIDialogScreenWithBackground() {
+	if (!MIPSComp::jit) {
+		return;
+	}
 	JitBlockCacheDebugInterface *blockCacheDebug = MIPSComp::jit->GetBlockCacheDebugInterface();
 	// The only defaults that make sense.
 	if (blockCacheDebug->SupportsProfiling()) {
diff --git a/UI/JitCompareScreen.h b/UI/JitCompareScreen.h
index 8a3828f1e4..0935ca3315 100644
--- a/UI/JitCompareScreen.h
+++ b/UI/JitCompareScreen.h
@@ -16,15 +16,15 @@ private:
 	// Uses the current ListType
 	void FillBlockList();
 
-	UI::LinearLayout *comparisonView_;
-	UI::LinearLayout *leftDisasm_;
-	UI::LinearLayout *rightDisasm_;
+	UI::LinearLayout *comparisonView_ = nullptr;
+	UI::LinearLayout *leftDisasm_ = nullptr;
+	UI::LinearLayout *rightDisasm_ = nullptr;
 
-	UI::LinearLayout *blockListView_;
-	UI::LinearLayout *blockListContainer_;
+	UI::LinearLayout *blockListView_ = nullptr;
+	UI::LinearLayout *blockListContainer_ = nullptr;
 
-	UI::LinearLayout *statsView_;
-	UI::LinearLayout *statsContainer_;
+	UI::LinearLayout *statsView_ = nullptr;
+	UI::LinearLayout *statsContainer_ = nullptr;
 
 	UI::EventReturn OnSelectBlock(UI::EventParams &e);
 	UI::EventReturn OnBlockAddress(UI::EventParams &e);
@@ -60,9 +60,9 @@ private:
 	int64_t sumExecutions_ = 0;
 	std::vector<int> blockList_;  // for BLOCK_LIST mode
 
-	UI::TextView *blockName_;
-	UI::TextEdit *blockAddr_;
-	UI::TextView *blockStats_;
+	UI::TextView *blockName_ = nullptr;
+	UI::TextEdit *blockAddr_ = nullptr;
+	UI::TextView *blockStats_ = nullptr;
 };
 
 class AddressPromptScreen : public PopupScreen {
diff --git a/UI/MiscScreens.cpp b/UI/MiscScreens.cpp
index c8edf028f0..2c16336792 100644
--- a/UI/MiscScreens.cpp
+++ b/UI/MiscScreens.cpp
@@ -1191,7 +1191,9 @@ void SettingInfoMessage::Show(std::string_view text, const UI::View *refView) {
 			}
 		}
 	}
-	text_->SetText(text);
+	if (text_) {
+		text_->SetText(text);
+	}
 	timeShown_ = time_now_d();
 }
 
diff --git a/UI/TabbedDialogScreen.cpp b/UI/TabbedDialogScreen.cpp
index 1758ac7344..c4b3dd81dd 100644
--- a/UI/TabbedDialogScreen.cpp
+++ b/UI/TabbedDialogScreen.cpp
@@ -116,8 +116,10 @@ void TabbedUIDialogScreenWithGameBackground::RecreateViews() {
 }
 
 void TabbedUIDialogScreenWithGameBackground::EnsureTabs() {
-	_assert_(tabHolder_);
-	tabHolder_->EnsureAllCreated();
+	_dbg_assert_(tabHolder_);
+	if (tabHolder_) {
+		tabHolder_->EnsureAllCreated();
+	}
 }
 
 void TabbedUIDialogScreenWithGameBackground::ApplySearchFilter() {