diff --git a/src/utils/os_unix.c b/src/utils/os_unix.c
index 9a2465ad3..4e117585b 100644
--- a/src/utils/os_unix.c
+++ b/src/utils/os_unix.c
@@ -315,14 +315,21 @@ char * os_readfile(const char *name, size_t *len)
 {
 	FILE *f;
 	char *buf;
+	long pos;
 
 	f = fopen(name, "rb");
 	if (f == NULL)
 		return NULL;
 
-	fseek(f, 0, SEEK_END);
-	*len = ftell(f);
-	fseek(f, 0, SEEK_SET);
+	if (fseek(f, 0, SEEK_END) < 0 || (pos = ftell(f)) < 0) {
+		fclose(f);
+		return NULL;
+	}
+	*len = pos;
+	if (fseek(f, 0, SEEK_SET) < 0) {
+		fclose(f);
+		return NULL;
+	}
 
 	buf = os_malloc(*len);
 	if (buf == NULL) {