diff --git a/man3/gcvt.3 b/man3/gcvt.3
index 2d7049b16..77d910abf 100644
--- a/man3/gcvt.3
+++ b/man3/gcvt.3
@@ -34,7 +34,7 @@ gcvt \- convert a floating-point number to a string
 .nf
 .B #include <stdlib.h>
 .sp
-.BI "char *gcvt(double " number ", size_t " ndigit ", char *" buf );
+.BI "char *gcvt(double " number ", int " ndigit ", char *" buf );
 .fi
 .sp
 .in -4n