Ensure read_long() reads the correct number of bytes from the index
diff --git a/libkmod/libkmod-index.c b/libkmod/libkmod-index.c
index 2136a96..0c49868 100644
--- a/libkmod/libkmod-index.c
+++ b/libkmod/libkmod-index.c
@@ -126,7 +126,7 @@
 	uint32_t l;
 
 	errno = 0;
-	if (fread(&l, sizeof(uint32_t), 1, in) <= 0)
+	if (fread(&l, sizeof(uint32_t), 1, in) != sizeof(uint32_t))
 		read_error();
 	return ntohl(l);
 }