diff --git a/docs/libpsl/libpsl-sections.txt b/docs/libpsl/libpsl-sections.txt
index 4c73e47..2c43358 100644
--- a/docs/libpsl/libpsl-sections.txt
+++ b/docs/libpsl/libpsl-sections.txt
@@ -16,6 +16,7 @@ psl_builtin_compile_time
 psl_builtin_file_time
 psl_builtin_sha1sum
 psl_builtin_filename
+psl_builtin_outdated
 psl_is_cookie_domain_acceptable
 psl_get_version
 psl_str_to_utf8lower
diff --git a/include/libpsl.h b/include/libpsl.h
index c059198..aa223e4 100644
--- a/include/libpsl.h
+++ b/include/libpsl.h
@@ -113,7 +113,9 @@ const char *
 /* returns library version */
 const char *
 	psl_get_version(void);
-
+/* returns wether the built-in data is outdated or not */
+int
+	psl_builtin_outdated(void);
 
 #ifdef  __cplusplus
 }
diff --git a/src/psl.c b/src/psl.c
index d311778..6108aef 100644
--- a/src/psl.c
+++ b/src/psl.c
@@ -54,6 +54,9 @@
 #	define ngettext(STRING1,STRING2,N) STRING2
 #endif
 
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -84,6 +87,7 @@
 #endif
 
 #include <libpsl.h>
+#include <bits/stat.h>
 
 /* number of elements within an array */
 #define countof(a) (sizeof(a)/sizeof(*(a)))
@@ -951,6 +955,29 @@ const char *psl_builtin_filename(void)
 	return _psl_filename;
 }
 
+/**
+ * psl_builtin_outdated:
+ *
+ * This function checks if the built-in data is older than the file it has been created from.
+ * If it is, it might be a good idea for the application to reload the PSL.
+ * The mtime is taken as reference.
+ *
+ * If the PSL file does not exist, it is assumed that the built-in data is not outdated.
+ *
+ * Returns: 1 if the built-in is outdated, 0 otherwise.
+ *
+ * Since: 0.10.0
+ */
+int psl_builtin_outdated(void)
+{
+	struct stat st;
+
+	if (stat(_psl_filename, &st) == 0 && st.st_mtime > _psl_file_time)
+		return 0;
+
+	return 1;
+}
+
 /**
  * psl_get_version:
  *