diff --git a/tests/check_path.c b/tests/check_path.c
index 0d6a73b..f12f950 100644
--- a/tests/check_path.c
+++ b/tests/check_path.c
@@ -26,8 +26,9 @@
 
 #define CHECK(code) \
 	{ \
-		if (code) \
-			FAIL(#code ": %s", fdt_strerror(code)); \
+		int err = (code); \
+		if (err) \
+			FAIL(#code ": %s", fdt_strerror(err)); \
 	}
 
 /* 4k ought to be enough for anybody */
diff --git a/tests/overlay.c b/tests/overlay.c
index 961ed60..3093eec 100644
--- a/tests/overlay.c
+++ b/tests/overlay.c
@@ -27,8 +27,9 @@
 
 #define CHECK(code) \
 	{ \
-		if (code) \
-			FAIL(#code ": %s", fdt_strerror(code)); \
+		int err = (code); \
+		if (err) \
+			FAIL(#code ": %s", fdt_strerror(err)); \
 	}
 
 /* 4k ought to be enough for anybody */