diff --git a/src/ConvertUTF.cpp b/src/ConvertUTF.cpp
index f7e5915d..c99b7d33 100644
--- a/src/ConvertUTF.cpp
+++ b/src/ConvertUTF.cpp
@@ -268,9 +268,9 @@ ConversionResult ConvertUTF16toUTF8 (
             target -= bytesToWrite; result = targetExhausted; break;
         }
         switch (bytesToWrite) { /* note: everything falls through. */
-            case 4: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
-            case 3: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
-            case 2: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
+            case 4: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6; // Intentional fallthrough
+            case 3: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6; // Intentional fallthrough
+            case 2: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6; // Intentional fallthrough
             case 1: *--target =  (UTF8)(ch | firstByteMark[bytesToWrite]);
         }
         target += bytesToWrite;
@@ -299,10 +299,9 @@ static Boolean isLegalUTF8(const UTF8 *source, int length) {
     switch (length) {
     default: return false;
         /* Everything else falls through when "true"... */
-    case 4: if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false;
-    case 3: if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false;
+    case 4: if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false; // Intentional fallthrough
+    case 3: if ((a = (*--srcptr)) < 0x80 || a > 0xBF) return false; // Intentional fallthrough
     case 2: if ((a = (*--srcptr)) > 0xBF) return false;
-
         switch (*source) {
             /* no fall-through in this inner switch */
             case 0xE0: if (a < 0xA0) return false; break;
@@ -311,7 +310,7 @@ static Boolean isLegalUTF8(const UTF8 *source, int length) {
             case 0xF4: if (a > 0x8F) return false; break;
             default:   if (a < 0x80) return false;
         }
-
+    // Intentional fallthrough
     case 1: if (*source >= 0x80 && *source < 0xC2) return false;
     }
     if (*source > 0xF4) return false;
@@ -355,11 +354,11 @@ ConversionResult ConvertUTF8toUTF16 (
          * The cases all fall through. See "Note A" below.
          */
         switch (extraBytesToRead) {
-            case 5: ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */
-            case 4: ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */
-            case 3: ch += *source++; ch <<= 6;
-            case 2: ch += *source++; ch <<= 6;
-            case 1: ch += *source++; ch <<= 6;
+            case 5: ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */ // Intentional fallthrough
+            case 4: ch += *source++; ch <<= 6; /* remember, illegal UTF-8 */ // Intentional fallthrough
+            case 3: ch += *source++; ch <<= 6; // Intentional fallthrough
+            case 2: ch += *source++; ch <<= 6; // Intentional fallthrough
+            case 1: ch += *source++; ch <<= 6; // Intentional fallthrough
             case 0: ch += *source++;
         }
         ch -= offsetsFromUTF8[extraBytesToRead];
@@ -446,9 +445,9 @@ ConversionResult ConvertUTF32toUTF8 (
             target -= bytesToWrite; result = targetExhausted; break;
         }
         switch (bytesToWrite) { /* note: everything falls through. */
-            case 4: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
-            case 3: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
-            case 2: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6;
+            case 4: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6; // Intentional fallthrough
+            case 3: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6; // Intentional fallthrough
+            case 2: *--target = (UTF8)((ch | byteMark) & byteMask); ch >>= 6; // Intentional fallthrough
             case 1: *--target = (UTF8) (ch | firstByteMark[bytesToWrite]);
         }
         target += bytesToWrite;
@@ -481,11 +480,11 @@ ConversionResult ConvertUTF8toUTF32 (
          * The cases all fall through. See "Note A" below.
          */
         switch (extraBytesToRead) {
-            case 5: ch += *source++; ch <<= 6;
-            case 4: ch += *source++; ch <<= 6;
-            case 3: ch += *source++; ch <<= 6;
-            case 2: ch += *source++; ch <<= 6;
-            case 1: ch += *source++; ch <<= 6;
+            case 5: ch += *source++; ch <<= 6; // Intentional fallthrough
+            case 4: ch += *source++; ch <<= 6; // Intentional fallthrough
+            case 3: ch += *source++; ch <<= 6; // Intentional fallthrough
+            case 2: ch += *source++; ch <<= 6; // Intentional fallthrough
+            case 1: ch += *source++; ch <<= 6; // Intentional fallthrough
             case 0: ch += *source++;
         }
         ch -= offsetsFromUTF8[extraBytesToRead];
diff --git a/src/linenoise.cpp b/src/linenoise.cpp
index 8ee8984d..42c8638d 100644
--- a/src/linenoise.cpp
+++ b/src/linenoise.cpp
@@ -624,7 +624,20 @@ struct PromptBase {            // a convenience struct for grouping prompt info
   int promptPreviousLen;       // help erasing
   int promptErrorCode;         // error code (invalid UTF-8) or zero
 
-  PromptBase() : promptPreviousInputLen(0) {}
+  PromptBase() :
+    promptText(0),
+    promptCharWidths(nullptr),
+    promptChars(0),
+    promptBytes(0),
+    promptExtraLines(0),
+    promptIndentation(0),
+    promptLastLinePosition(0),
+    promptPreviousInputLen(0),
+    promptCursorRowOffset(0),
+    promptScreenColumns(0),
+    promptPreviousLen(0),
+    promptErrorCode(0)
+  {}
 
   bool write() {
     if (write32(1, promptText.get(), promptBytes) == -1) return false;
@@ -727,7 +740,7 @@ struct DynamicPrompt : public PromptBase {
   int direction;           // current search direction, 1=forward, -1=reverse
 
   DynamicPrompt(PromptBase& pi, int initialDirection)
-      : searchTextLen(0), direction(initialDirection) {
+      : searchCharWidths(nullptr), searchTextLen(0), direction(initialDirection) {
     promptScreenColumns = pi.promptScreenColumns;
     promptCursorRowOffset = 0;
     Utf32String emptyString(1);