diff --git a/Source/Tests/preprocessor.nsi b/Source/Tests/preprocessor.nsi
index 7e00a8ec..b025b6c4 100644
--- a/Source/Tests/preprocessor.nsi
+++ b/Source/Tests/preprocessor.nsi
@@ -10,6 +10,8 @@ this should not be executed, so no error should be raised
 code inside comments should not be executed
 !ifdef
 */
+# invalid preprocessor should be ignored
+!hello
 !endif
 
 !ifdef d1
diff --git a/Source/build.h b/Source/build.h
index 042966c6..13b97d7e 100644
--- a/Source/build.h
+++ b/Source/build.h
@@ -140,6 +140,7 @@ class CEXEBuild {
     void update_exehead(const unsigned char *new_exehead, size_t new_size);
 
     // tokens.cpp
+    bool is_valid_token(char *s);
     int get_commandtoken(char *s, int *np, int *op, int *pos);
     int GetCurrentTokenPlace();
     int IsTokenPlacedRight(int pos, char *tok);
diff --git a/Source/script.cpp b/Source/script.cpp
index 9b9b6314..daef81e7 100644
--- a/Source/script.cpp
+++ b/Source/script.cpp
@@ -305,7 +305,7 @@ int CEXEBuild::doParse(const char *str)
   {
     bool ignore_line = cur_ifblock && (cur_ifblock->ignore || cur_ifblock->inherited_ignore);
     char first_char = *(char *) m_linebuild.get();
-    if (ignore_line && first_char!='!')
+    if (ignore_line && (first_char!='!' || !is_valid_token(line.gettoken_str(0))))
     {
       m_linebuild.resize(0);
       return PS_OK;
diff --git a/Source/tokens.cpp b/Source/tokens.cpp
index 512d80e7..09951c08 100644
--- a/Source/tokens.cpp
+++ b/Source/tokens.cpp
@@ -297,6 +297,14 @@ void CEXEBuild::print_help(char *commandname)
 
 }
 
+bool CEXEBuild::is_valid_token(char *s)
+{
+  for (int x = 0; x < TOK__LAST; x ++)
+    if (!stricmp(tokenlist[x].name,s)) 
+      return true;
+  return false;
+}
+
 int CEXEBuild::get_commandtoken(char *s, int *np, int *op, int *pos)
 {
   int x;