diff --git a/CHANGES b/CHANGES
index 48dce6e..5efbf45 100644
--- a/CHANGES
+++ b/CHANGES
@@ -14,6 +14,10 @@ Corrections:
 
 	Removed unused usleep() call from sycls.c
 
+	Unsetenv() was conditional in sysutils.c but not in xio-openssl.c thus
+	building failed on Solaris 9.
+	Thanks to Greg Earle for reporting this issue and providing a patch.
+	
 Porting:
 	In gcc version 10 the default changed from -fcommon to -fno-common.
 	Consequently, linking filan and procan failed with error
diff --git a/xio-openssl.c b/xio-openssl.c
index 132e8ea..e4c03a9 100644
--- a/xio-openssl.c
+++ b/xio-openssl.c
@@ -1243,7 +1243,9 @@ static int openssl_delete_cert_info(void) {
 	 const char *eq = strchr(*entry, '=');
 	 if (eq == NULL)  eq = *entry + strlen(*entry);
 	 envname[0] = '\0'; strncat(envname, *entry, eq-*entry);
+#if HAVE_UNSETENV
 	 Unsetenv(envname);
+#endif
       } else {
 	 ++entry;
       }