diff --git a/src/parser3.h b/src/parser3.h
index 335fb09..4fd54f6 100644
--- a/src/parser3.h
+++ b/src/parser3.h
@@ -245,7 +245,9 @@ inline PRESERVE_NONE WeaselJsonStatus scan_string(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus n_value(Parser3 *self, char *buf,
                                               char *bufEnd) {
-  assert(bufEnd - buf != 0);
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   if (auto s = skipWhitespace(buf, bufEnd)) {
     return s;
   }
@@ -349,7 +351,9 @@ inline PRESERVE_NONE WeaselJsonStatus n_value(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus n_object2(Parser3 *self, char *buf,
                                                 char *bufEnd) {
-  assert(bufEnd - buf != 0);
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   if (auto s = skipWhitespace(buf, bufEnd)) {
     return s;
   }
@@ -375,7 +379,9 @@ inline PRESERVE_NONE WeaselJsonStatus n_object2(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus n_object3(Parser3 *self, char *buf,
                                                 char *bufEnd) {
-  assert(bufEnd - buf != 0);
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   if (auto s = skipWhitespace(buf, bufEnd)) {
     return s;
   }
@@ -399,7 +405,9 @@ inline PRESERVE_NONE WeaselJsonStatus n_object3(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus n_array2(Parser3 *self, char *buf,
                                                char *bufEnd) {
-  assert(bufEnd - buf != 0);
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   if (auto s = skipWhitespace(buf, bufEnd)) {
     return s;
   }
@@ -420,7 +428,9 @@ inline PRESERVE_NONE WeaselJsonStatus n_array2(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus n_array3(Parser3 *self, char *buf,
                                                char *bufEnd) {
-  assert(bufEnd - buf != 0);
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   if (auto s = skipWhitespace(buf, bufEnd)) {
     return s;
   }
@@ -444,7 +454,9 @@ inline PRESERVE_NONE WeaselJsonStatus n_array3(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus n_string(Parser3 *self, char *buf,
                                                char *bufEnd) {
-  assert(bufEnd - buf != 0);
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   if (auto s = skipWhitespace(buf, bufEnd)) {
     return s;
   }
@@ -468,6 +480,9 @@ inline int32_t read4_hex(const char *buf) {
 
 inline PRESERVE_NONE WeaselJsonStatus n_string2(Parser3 *self, char *buf,
                                                 char *bufEnd) {
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   if (auto s = scan_string(self, buf, bufEnd)) {
     return s;
   }
@@ -495,8 +510,8 @@ inline PRESERVE_NONE WeaselJsonStatus n_string2(Parser3 *self, char *buf,
         if (0xd800 <= codepoint && codepoint <= 0xdfff) {
           // utf-16 surrogate
           int32_t codepoint2 = read4_hex(buf + 2);
-          if (!(buf[0] == '\\' && buf[1] == 'u' && codepoint2 >= 0))
-              [[unlikely]] {
+          if (!(buf[0] == '\\' && buf[1] == 'u' && 0xdc00 <= codepoint2 &&
+                codepoint2 <= 0xdfff)) [[unlikely]] {
             return WeaselJson_REJECT;
           }
           codepoint =
@@ -550,6 +565,9 @@ inline PRESERVE_NONE WeaselJsonStatus n_string2(Parser3 *self, char *buf,
 inline PRESERVE_NONE WeaselJsonStatus n_string_following_escape(Parser3 *self,
                                                                 char *buf,
                                                                 char *bufEnd) {
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   assert(self->strDfa.accept());
   switch (*buf) {
   case '"':
@@ -578,6 +596,9 @@ inline PRESERVE_NONE WeaselJsonStatus n_string_following_escape(Parser3 *self,
 
 inline PRESERVE_NONE WeaselJsonStatus t_hex(Parser3 *self, char *buf,
                                             char *bufEnd) {
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   auto hexVal = tables.hex[uint8_t(*buf)];
   if (hexVal < 0) [[unlikely]] {
     return WeaselJson_REJECT;
@@ -591,6 +612,9 @@ inline PRESERVE_NONE WeaselJsonStatus t_hex(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus t_hex2(Parser3 *self, char *buf,
                                              char *bufEnd) {
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   auto hexVal = tables.hex[uint8_t(*buf)];
   if (hexVal < 0) [[unlikely]] {
     return WeaselJson_REJECT;
@@ -655,6 +679,9 @@ inline PRESERVE_NONE WeaselJsonStatus t_hex2(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus t_hex3(Parser3 *self, char *buf,
                                              char *bufEnd) {
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   auto hexVal = tables.hex[uint8_t(*buf)];
   if (hexVal < 0) [[unlikely]] {
     return WeaselJson_REJECT;
@@ -703,6 +730,9 @@ inline PRESERVE_NONE WeaselJsonStatus t_hex3(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus n_true(Parser3 *self, char *buf,
                                              char *bufEnd) {
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   if (*buf == 'e') {
     ++buf;
     self->pop();
@@ -715,6 +745,9 @@ inline PRESERVE_NONE WeaselJsonStatus n_true(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus n_false(Parser3 *self, char *buf,
                                               char *bufEnd) {
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   if (*buf == 'e') {
     ++buf;
     self->pop();
@@ -727,6 +760,9 @@ inline PRESERVE_NONE WeaselJsonStatus n_false(Parser3 *self, char *buf,
 
 inline PRESERVE_NONE WeaselJsonStatus n_null(Parser3 *self, char *buf,
                                              char *bufEnd) {
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   if (*buf == 'l') {
     ++buf;
     self->pop();
@@ -740,8 +776,10 @@ inline PRESERVE_NONE WeaselJsonStatus n_null(Parser3 *self, char *buf,
 template <char kChar, bool kSkipWhitespace = false>
 inline PRESERVE_NONE WeaselJsonStatus singleChar(Parser3 *self, char *buf,
                                                  char *bufEnd) {
+  if (buf == bufEnd) [[unlikely]] {
+    return WeaselJson_REJECT;
+  }
   if constexpr (kSkipWhitespace) {
-    assert(bufEnd - buf != 0);
     if (auto s = skipWhitespace(buf, bufEnd)) {
       return s;
     }
@@ -823,16 +861,9 @@ constexpr inline struct ContinuationTable {
     symbolNames[T_HEX3] = "t_hex3";
     symbolNames[T_EOF] = "t_eof";
     symbolNames[T_BACKSLASH] = "singleChar<'\\'>";
-
-    // All others can assume that there's at least one byte when they're
-    // called
-    acceptsEmptyString[N_NUMBER] = true;
-    acceptsEmptyString[N_WHITESPACE] = true;
-    acceptsEmptyString[T_EOF] = true;
   }
   Continuation continuations[N_SYMBOL_COUNT]{};
   const char *symbolNames[N_SYMBOL_COUNT]{};
-  bool acceptsEmptyString[N_SYMBOL_COUNT]{};
 } symbolTables;
 
 inline PRESERVE_NONE WeaselJsonStatus Parser3::keepGoing(Parser3 *self,
@@ -876,9 +907,6 @@ inline PRESERVE_NONE WeaselJsonStatus Parser3::keepGoing(Parser3 *self,
       }
       return WeaselJson_AGAIN;
     }
-    if (!symbolTables.acceptsEmptyString[self->top()]) [[unlikely]] {
-      return WeaselJson_REJECT;
-    }
   }
   // printf("%s\n", symbolTables.symbolNames[self->top()]);
   MUSTTAIL return symbolTables.continuations[self->top()](self, buf, bufEnd);