diff --git a/st.c b/st.c
index 596d6c6..4ae9bcf 100644
--- a/st.c
+++ b/st.c
@@ -148,7 +148,7 @@ typedef struct {
 /* ESC '[' [[ [<priv>] <arg> [;]] <mode> [<mode>]] */
 typedef struct {
 	char buf[ESC_BUF_SIZ]; /* raw string */
-	int len;               /* raw string length */
+	size_t len;            /* raw string length */
 	char priv;
 	int arg[ESC_ARG_SIZ];
 	int narg;              /* nb of args */
@@ -160,7 +160,7 @@ typedef struct {
 typedef struct {
 	char type;             /* ESC type ... */
 	char buf[STR_BUF_SIZ]; /* raw string */
-	int len;               /* raw string length */
+	size_t len;            /* raw string length */
 	char *args[STR_ARG_SIZ];
 	int narg;              /* nb of args */
 } STREscape;
@@ -1928,7 +1928,7 @@ csihandle(void)
 void
 csidump(void)
 {
-	int i;
+	size_t i;
 	uint c;
 
 	fprintf(stderr, "ESC[");
@@ -2046,7 +2046,7 @@ strparse(void)
 void
 strdump(void)
 {
-	int i;
+	size_t i;
 	uint c;
 
 	fprintf(stderr, "ESC%c", strescseq.type);