diff --git a/less.h b/less.h
index 43e2cc47..2f880eb1 100644
--- a/less.h
+++ b/less.h
@@ -580,8 +580,8 @@ struct ansi_state;
 void postoa LESSPARAMS ((POSITION, char*));
 void linenumtoa LESSPARAMS ((LINENUM, char*));
 void inttoa LESSPARAMS ((int, char*));
-int lstrtoi LESSPARAMS ((char*, char**));
-POSITION lstrtopos LESSPARAMS ((char*, char**));
+int lstrtoi LESSPARAMS ((char*, char**, int));
+POSITION lstrtopos LESSPARAMS ((char*, char**, int));
 #if MSDOS_COMPILER==WIN32C
 int pclose LESSPARAMS ((FILE*));
 #endif
diff --git a/lessecho.c b/lessecho.c
index 5cd660db..c6fa4c93 100644
--- a/lessecho.c
+++ b/lessecho.c
@@ -70,10 +70,10 @@ pr_error(s)
 }
 
 	static long
-lstrtol(s, radix, pend)
+lstrtol(s, pend, radix)
 	char *s;
-	int radix;
 	char **pend;
+	int radix;
 {
 	int v;
 	int neg = 0;
@@ -210,7 +210,7 @@ main(argc, argv)
 			closequote = *++arg;
 			break;
 		case 'd':
-			closequote = lstrtol(++arg, 0, &s);
+			closequote = lstrtol(++arg, &s, 0);
 			if (s == arg)
 				pr_error("Missing number after -d");
 			break;
@@ -221,7 +221,7 @@ main(argc, argv)
 				meta_escape = arg;
 			break;
 		case 'f':
-			meta_escape_buf[0] = lstrtol(++arg, 0, &s);
+			meta_escape_buf[0] = lstrtol(++arg, &s, 0);
 			meta_escape_buf[1] = '\0';
 			meta_escape = meta_escape_buf;
 			if (s == arg)
@@ -231,7 +231,7 @@ main(argc, argv)
 			openquote = *++arg;
 			break;
 		case 'p':
-			openquote = lstrtol(++arg, 0, &s);
+			openquote = lstrtol(++arg, &s, 0);
 			if (s == arg)
 				pr_error("Missing number after -p");
 			break;
@@ -239,7 +239,7 @@ main(argc, argv)
 			add_metachar(*++arg);
 			break;
 		case 'n':
-			add_metachar(lstrtol(++arg, 0, &s));
+			add_metachar(lstrtol(++arg, &s, 0));
 			if (s == arg)
 				pr_error("Missing number after -n");
 			break;
diff --git a/lesskey.c b/lesskey.c
index 39ebe8b9..f8e4a6eb 100644
--- a/lesskey.c
+++ b/lesskey.c
@@ -123,11 +123,12 @@ lesskey_parse_error(s)
 }
 
 	int
-lstrtoi(buf, ebuf)
+lstrtoi(buf, ebuf, radix)
 	char *buf;
 	char **ebuf;
+	int radix;
 {
-	return (int) strtol(buf, ebuf, 10);
+	return (int) strtol(buf, ebuf, radix);
 }
 
 	void *
diff --git a/lesskey_parse.c b/lesskey_parse.c
index 5d761eba..0f8318bd 100644
--- a/lesskey_parse.c
+++ b/lesskey_parse.c
@@ -21,7 +21,7 @@
 extern void lesskey_parse_error(char *msg);
 extern char *homefile(char *filename);
 extern void *ecalloc(int count, unsigned int size);
-extern int lstrtoi(char *str, char **end);
+extern int lstrtoi(char *str, char **end, int radix);
 extern char version[];
 
 static int linenum;
@@ -439,7 +439,7 @@ version_line(s, tables)
 		return (NULL);
 	}
 	s = skipsp(s);
-	ver = lstrtoi(s, &e);
+	ver = lstrtoi(s, &e, 10);
 	if (e == s)
 	{
 		parse_error("non-numeric version number in #version line", "");
@@ -678,7 +678,7 @@ parse_lesskey(infile, tables)
 	errors = 0;
 	linenum = 0;
 	if (less_version == 0)
-		less_version = lstrtoi(version, NULL);
+		less_version = lstrtoi(version, NULL, 10);
 
 	/*
 	 * Open the input file.
diff --git a/mark.c b/mark.c
index f3bf0c4f..4de1d094 100644
--- a/mark.c
+++ b/mark.c
@@ -446,13 +446,13 @@ restore_mark(line)
 	if (m == NULL)
 		return;
 	skip_whitespace;
-	ln = lstrtoi(line, &line);
+	ln = lstrtoi(line, &line, 10);
 	if (ln < 1)
 		ln = 1;
 	if (ln > sc_height)
 		ln = sc_height;
 	skip_whitespace;
-	pos = lstrtopos(line, &line);
+	pos = lstrtopos(line, &line, 10);
 	skip_whitespace;
 	cmark(m, NULL_IFILE, pos, ln);
 	m->m_filename = save(line);
diff --git a/output.c b/output.c
index 3fed3df3..0017c525 100644
--- a/output.c
+++ b/output.c
@@ -504,15 +504,17 @@ TYPE_TO_A_FUNC(inttoa, int)
  * Convert an string to an integral type.
  */
 #define STR_TO_TYPE_FUNC(funcname, type) \
-type funcname(buf, ebuf) \
+type funcname(buf, ebuf, radix) \
 	char *buf; \
 	char **ebuf; \
+	int radix; \
 { \
 	type val = 0; \
 	for (;; buf++) { \
 		char c = *buf; \
-		if (c < '0' || c > '9') break; \
-		val = 10 * val + c - '0'; \
+		int digit = (c >= '0' && c <= '9') ? c - '0' : (c >= 'a' && c <= 'f') ? c - 'a' + 10 : (c >= 'A' && c <= 'F') ? c - 'A' + 10 : -1; \
+		if (digit < 0 || digit >= radix) break; \
+		val = radix * val + digit; \
 	} \
 	if (ebuf != NULL) *ebuf = buf; \
 	return val; \
diff --git a/screen.c b/screen.c
index 7c903ab6..c05c50ed 100644
--- a/screen.c
+++ b/screen.c
@@ -1662,7 +1662,7 @@ ltputs(str, affcnt, f_putc)
 				do_tputs(str2, affcnt, f_putc);
 				str += slen + 2;
 				/* Perform the delay. */
-				delay = lstrtoi(str, &str);
+				delay = lstrtoi(str, &str, 10);
 				if (*str == '*')
 					delay *= affcnt;
 				flush();
@@ -2469,7 +2469,7 @@ parse_color6(ps)
 	} else
 	{
 		char *ops = *ps;
-		int color = lstrtoi(ops, ps);
+		int color = lstrtoi(ops, ps, 10);
 		if (*ps == ops)
 			return CV_ERROR;
 		return color;