diff --git a/Makefile b/Makefile
index 0f58f03..3b668c7 100644
--- a/Makefile
+++ b/Makefile
@@ -20,7 +20,7 @@ INSTALL_EXEC= $(INSTALL) -m 0755
 INSTALL_DATA= $(INSTALL) -m 0644
 
 # C compilation flags
-CFLAGS   = -DPT_DEBUG -O2 -std=c99 -pedantic -Wall -Wextra
+CFLAGS   = -DPT_DEBUG -O2 -std=c99 -pedantic -Wall -Wextra -Wformat-security
 CPPFLAGS = -I$(LUA_INCDIR)
 LIBFLAG  = -fPIC -shared
 
diff --git a/pt-run.c b/pt-run.c
index 64edf87..2cbb1ff 100644
--- a/pt-run.c
+++ b/pt-run.c
@@ -149,7 +149,7 @@ static void pt_run_dbg_print(const char *buf, bool *ellipsis, int *pframes, int
         || ((nframes - *pframes) <= PT_RUN_TRACEBACK_BOTTOM_THRESHOLD);
 
     if(luai_likely(should_print))
-        fprintf(stderr, buf);
+        fprintf(stderr, "%s", buf);
     else if(*ellipsis) {
         fprintf(stderr, "\n    ... (Skipped %d frames) ...\n\n",
             nframes - (PT_RUN_TRACEBACK_TOP_THRESHOLD