diff --git a/src/fuzz.c b/src/fuzz.c
index 76b13c5..acd4ebf 100644
--- a/src/fuzz.c
+++ b/src/fuzz.c
@@ -44,8 +44,8 @@ static enum fuzzing
 fuzzing;
 
 /* Per-offset byte protection */
-static unsigned int *ranges = NULL;
-static unsigned int ranges_static[512];
+static int *ranges = NULL;
+static int ranges_static[512];
 
 /* Per-value byte protection */
 static int protect[256];
@@ -109,7 +109,7 @@ void _zz_refuse(char const *list)
     readchars(refuse, list);
 }
 
-void _zz_fuzz(int fd, volatile uint8_t *buf, uint64_t len)
+void _zz_fuzz(int fd, volatile uint8_t *buf, int64_t len)
 {
     int64_t start, stop;
     int64_t pos = _zz_getpos(fd);
diff --git a/src/fuzz.h b/src/fuzz.h
index 8f72501..0ac3b0e 100644
--- a/src/fuzz.h
+++ b/src/fuzz.h
@@ -21,5 +21,5 @@ extern void _zz_bytes(char const *);
 extern void _zz_protect(char const *);
 extern void _zz_refuse(char const *);
 
-extern void _zz_fuzz(int, volatile uint8_t *, uint64_t);
+extern void _zz_fuzz(int, volatile uint8_t *, int64_t);
 
diff --git a/src/libzzuf.h b/src/libzzuf.h
index 55b46ae..53072d9 100644
--- a/src/libzzuf.h
+++ b/src/libzzuf.h
@@ -38,7 +38,7 @@ struct fuzz
 #ifdef HAVE_FGETLN
     char *tmp;
 #endif
-    int uflag; uint64_t upos; uint8_t uchar; /* ungetc stuff */
+    int uflag; int64_t upos; uint8_t uchar; /* ungetc stuff */
     uint8_t data[CHUNKBYTES];
 };