1 files changed, 3 insertions, 3 deletions

diff --git a/tools/100_checkdata/checkdata.c b/tools/100_checkdata/checkdata.c
index eefb063..c284aa4 100644
--- a/tools/100_checkdata/checkdata.c
+++ b/tools/100_checkdata/checkdata.c
@@ -5,7 +5,7 @@ char *solver, *filename;
 
 static void
 run(void) {
-        long long int size, result;
+        long long int size, sizeread, result;
         char dataid[NISSY_SIZE_DATAID];
         unsigned char *buf;
         FILE *f;
@@ -23,9 +23,9 @@ run(void) {
         }
 
         buf = malloc(size);
-        fread(buf, size, 1, f);
+        sizeread = fread(buf, size, 1, f);
         fclose(f);
-        result = nissy_checkdata(size, buf);
+        result = sizeread == 1 && nissy_checkdata(size, buf);
         free(buf);
 
         printf("checkdata %s\n", result == 0 ? "succeeded" : "failed");