1 files changed, 1 insertions, 1 deletions
diff --git a/src/main.c b/src/main.c
index c4e6849..eb2c09f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -295,7 +295,7 @@ void initialize_output_filters(void)
 	if ( !(m4 = getenv("M4"))) {
 		m4 = M4;
 	}
-	filter_create_ext(output_chain, m4, "-P", 0);
+	filter_create_ext(output_chain, m4, "-P", (char *) 0);
 	filter_create_int(output_chain, filter_fix_linedirs, NULL);
 
 	/* For debugging, only run the requested number of filters. */