1 files changed, 5 insertions, 0 deletions

diff --git a/src/solvers/h48/checkdata.h b/src/solvers/h48/checkdata.h
index 948ac67..e2fa38c 100644
--- a/src/solvers/h48/checkdata.h
+++ b/src/solvers/h48/checkdata.h
@@ -1,3 +1,6 @@
+#ifndef SOLVERS_H48_CHECKDATA_H
+#define SOLVERS_H48_CHECKDATA_H
+
 STATIC long long checkdata_h48(
     const char *, unsigned long long, const unsigned char *);
 
@@ -194,3 +197,5 @@ checkdata_h48(
 
         return NISSY_OK;
 }
+
+#endif /* SOLVERS_H48_CHECKDATA_H */