diff --git a/src/lib-stream.c b/src/lib-stream.c
index 884015c..2b1e803 100644
--- a/src/lib-stream.c
+++ b/src/lib-stream.c
@@ -300,8 +300,8 @@ size_t NEW(fread)(void *ptr, size_t size, size_t nmemb, FILE *stream)
         ret = ORIG(fn)(stream); \
         _zz_unlock(fd); \
         FGETC_FUZZ \
-        if(ret < 0) \
-            debug("%s([%i]) = %i", __func__, fd, ret); \
+        if(ret == EOF) \
+            debug("%s([%i]) = EOF", __func__, fd); \
         else \
             debug("%s([%i]) = '%c'", __func__, fd, ret); \
     } while(0)
@@ -404,8 +404,8 @@ int NEW(ungetc)(int c, FILE *stream)
 #endif
     }
 
-    if(ret < 0)
-        debug("%s(0x%02x, [%i]) = %i", __func__, c, fd, ret);
+    if(ret == EOF)
+        debug("%s(0x%02x, [%i]) = EOF", __func__, c, fd);
     else
         debug("%s(0x%02x, [%i]) = '%c'", __func__, c, fd, ret);