diff --git a/panda/src/egg/lexer.cxx.prebuilt b/panda/src/egg/lexer.cxx.prebuilt
index f0b0a2b4ec..06e6dd0123 100644
--- a/panda/src/egg/lexer.cxx.prebuilt
+++ b/panda/src/egg/lexer.cxx.prebuilt
@@ -1195,12 +1195,12 @@ scan_quoted_string() {
 
   int c;
   c = read_char(line, col);
-  while (c != '"' && c != EOF) {
+  while (c != '"' && c != 0 && c != EOF) {
     result += c;
     c = read_char(line, col);
   }
 
-  if (c == EOF) {
+  if (c == 0 || c == EOF) {
     eggyyerror("This quotation mark is unterminated.");
   }
 
@@ -1224,7 +1224,7 @@ eat_c_comment() {
   
   last_c = '\0';
   c = read_char(line, col);
-  while (c != EOF && !(last_c == '*' && c == '/')) {
+  while (c != 0 && c != EOF && !(last_c == '*' && c == '/')) {
     if (last_c == '/' && c == '*') {
       std::ostringstream errmsg;
       errmsg << "This comment contains a nested /* symbol at line "
@@ -1236,7 +1236,7 @@ eat_c_comment() {
     c = read_char(line, col);
   }
 
-  if (c == EOF) {
+  if (c == 0 || c == EOF) {
     eggyyerror("This comment marker is unclosed.");
   }
 
diff --git a/panda/src/egg/lexer.lxx b/panda/src/egg/lexer.lxx
index 88aed62e46..c4b6f88028 100644
--- a/panda/src/egg/lexer.lxx
+++ b/panda/src/egg/lexer.lxx
@@ -250,12 +250,12 @@ scan_quoted_string() {
 
   int c;
   c = read_char(line, col);
-  while (c != '"' && c != EOF) {
+  while (c != '"' && c != 0 && c != EOF) {
     result += c;
     c = read_char(line, col);
   }
 
-  if (c == EOF) {
+  if (c == 0 || c == EOF) {
     eggyyerror("This quotation mark is unterminated.");
   }
 
@@ -279,7 +279,7 @@ eat_c_comment() {
 
   last_c = '\0';
   c = read_char(line, col);
-  while (c != EOF && !(last_c == '*' && c == '/')) {
+  while (c != 0 && c != EOF && !(last_c == '*' && c == '/')) {
     if (last_c == '/' && c == '*') {
       std::ostringstream errmsg;
       errmsg << "This comment contains a nested /* symbol at line "
@@ -291,7 +291,7 @@ eat_c_comment() {
     c = read_char(line, col);
   }
 
-  if (c == EOF) {
+  if (c == 0 || c == EOF) {
     eggyyerror("This comment marker is unclosed.");
   }