diff --git a/include/kvm.h b/include/kvm.h
index 6c437b919c97..fb2d22435fee 100644
--- a/include/kvm.h
+++ b/include/kvm.h
@@ -61,8 +61,8 @@ kvm_t	 *kvm_open
 	    __P((const char *, const char *, const char *, int, const char *));
 kvm_t	 *kvm_openfiles
 	    __P((const char *, const char *, const char *, int, char *));
-int	  kvm_read __P((kvm_t *, unsigned long, void *, unsigned int));
-int	  kvm_write __P((kvm_t *, unsigned long, const void *, unsigned int));
+ssize_t	  kvm_read __P((kvm_t *, unsigned long, void *, size_t));
+ssize_t	  kvm_write __P((kvm_t *, unsigned long, const void *, size_t));
 /* Comment this out until it can be fixed correctly.
 ssize_t	  kvm_uread
 	    __P((kvm_t *, struct proc *, unsigned long, char *, size_t));
diff --git a/lib/libkvm/kvm.h b/lib/libkvm/kvm.h
index 6c437b919c97..fb2d22435fee 100644
--- a/lib/libkvm/kvm.h
+++ b/lib/libkvm/kvm.h
@@ -61,8 +61,8 @@ kvm_t	 *kvm_open
 	    __P((const char *, const char *, const char *, int, const char *));
 kvm_t	 *kvm_openfiles
 	    __P((const char *, const char *, const char *, int, char *));
-int	  kvm_read __P((kvm_t *, unsigned long, void *, unsigned int));
-int	  kvm_write __P((kvm_t *, unsigned long, const void *, unsigned int));
+ssize_t	  kvm_read __P((kvm_t *, unsigned long, void *, size_t));
+ssize_t	  kvm_write __P((kvm_t *, unsigned long, const void *, size_t));
 /* Comment this out until it can be fixed correctly.
 ssize_t	  kvm_uread
 	    __P((kvm_t *, struct proc *, unsigned long, char *, size_t));