diff --git a/kregexpeditor/gen_qregexplexer.cpp b/kregexpeditor/gen_qregexplexer.cpp
index 12dade3..b5ca999 100644
--- a/kregexpeditor/gen_qregexplexer.cpp
+++ b/kregexpeditor/gen_qregexplexer.cpp
@@ -493,7 +493,7 @@ static int input YY_PROTO(( void ));
 #endif
 #endif
 
-#if YY_STACK_USED
+#ifdef YY_STACK_USED
 static int yy_start_stack_ptr = 0;
 static int yy_start_stack_depth = 0;
 static int *yy_start_stack = 0;
@@ -1470,10 +1470,10 @@ FILE *file;
 	b->yy_input_file = file;
 	b->yy_fill_buffer = 1;
 
-#if YY_ALWAYS_INTERACTIVE
+#ifdef YY_ALWAYS_INTERACTIVE
 	b->yy_is_interactive = 1;
 #else
-#if YY_NEVER_INTERACTIVE
+#ifdef YY_NEVER_INTERACTIVE
 	b->yy_is_interactive = 0;
 #else
 	b->yy_is_interactive = file ? (isatty( fileno(file) ) > 0) : 0;
@@ -1764,7 +1764,7 @@ void *ptr;
 	free( ptr );
 	}
 
-#if YY_MAIN
+#ifdef YY_MAIN
 int main()
 	{
 	yylex();
diff --git a/kregexpeditor/gen_qregexpparser.cc b/kregexpeditor/gen_qregexpparser.cc
index f2ac58a..f72775b 100644
--- a/kregexpeditor/gen_qregexpparser.cc
+++ b/kregexpeditor/gen_qregexpparser.cc
@@ -182,7 +182,7 @@ typedef struct yyltype
 
 /* The parser invokes alloca or malloc; define the necessary symbols.  */
 
-# if YYSTACK_USE_ALLOCA
+# ifdef YYSTACK_USE_ALLOCA
 #  define YYSTACK_ALLOC alloca
 # else
 #  ifndef YYSTACK_USE_ALLOCA
@@ -569,7 +569,7 @@ int yydebug;
    SIZE_MAX < YYSTACK_BYTES (YYMAXDEPTH)
    evaluated with infinite-precision integer arithmetic.  */
 
-#if YYMAXDEPTH == 0
+#ifdef YYMAXDEPTH == 0
 # undef YYMAXDEPTH
 #endif