diff --git a/src/Instrumentation/KLN89/kln89_page_alt.cxx b/src/Instrumentation/KLN89/kln89_page_alt.cxx
index 0a0317834..cf8dea7db 100644
--- a/src/Instrumentation/KLN89/kln89_page_alt.cxx
+++ b/src/Instrumentation/KLN89/kln89_page_alt.cxx
@@ -52,7 +52,7 @@ void KLN89AltPage::Update(double dt) {
 				_kln89->_userBaroSetting = (int)((float)_kln89->_userBaroSetting * 0.0295301 * 100 + 0.5);
 			}
 			char buf[6];
-			snprintf(buf, 6, "%2i.%02i", _kln89->_userBaroSetting/100, _kln89->_userBaroSetting % 100);
+			snprintf(buf, sizeof(buf), "%2i.%02i", _kln89->_userBaroSetting/100, _kln89->_userBaroSetting % 100);
 			string s = buf;
 			if(!(_kln89->_mode == KLN89_MODE_CRSR && _uLinePos == 1 && _kln89->_blink)) {
 				_kln89->DrawText(s, 2, 7, 3);
@@ -69,7 +69,7 @@ void KLN89AltPage::Update(double dt) {
 				_kln89->_userBaroSetting = (int)(((float)_kln89->_userBaroSetting / 100.0) * 33.8637526 + 0.5);
 			}
 			char buf[5];
-			snprintf(buf, 5, "%4i", _kln89->_userBaroSetting);
+			snprintf(buf, sizeof(buf), "%4i", _kln89->_userBaroSetting);
 			string s = buf;
 			if(!(_kln89->_mode == KLN89_MODE_CRSR && _uLinePos == 1 && _kln89->_blink)) {
 				_kln89->DrawText(s, 2, 8, 3);
diff --git a/src/Instrumentation/KLN89/kln89_page_apt.cxx b/src/Instrumentation/KLN89/kln89_page_apt.cxx
index b64f79d6a..e9dd12cdb 100644
--- a/src/Instrumentation/KLN89/kln89_page_apt.cxx
+++ b/src/Instrumentation/KLN89/kln89_page_apt.cxx
@@ -150,7 +150,7 @@ void KLN89AptPage::Update(double dt) {
 			if(hrDiff != 0) {
 				_kln89->DrawText(ap->getLongitude() >= 0.0 ? "+" : "-", 2, 3, 2);
 				char buf[3];
-				snprintf(buf, 3, "%02i", hrDiff);
+				snprintf(buf, sizeof(buf), "%02i", hrDiff);
 				_kln89->DrawText((string)buf, 2, 4, 2);
 				_kln89->DrawText("(   DT)", 2, 6, 2);
 				if(ap->getLongitude() >= 0.0) {
@@ -159,7 +159,7 @@ void KLN89AptPage::Update(double dt) {
 					hrDiff--;
 				}
 				_kln89->DrawText(ap->getLongitude() >= 0.0 ? "+" : "-", 2, 7, 2);
-				snprintf(buf, 3, "%02i", hrDiff);
+				snprintf(buf, sizeof(buf), "%02i", hrDiff);
 				_kln89->DrawText((string)buf, 2, 8, 2);
 			}
 			// I guess we can make a heuristic guess as to fuel availability from the runway sizes
diff --git a/src/Instrumentation/KLN89/kln89_page_cal.cxx b/src/Instrumentation/KLN89/kln89_page_cal.cxx
index 74b0937e2..8973d4413 100644
--- a/src/Instrumentation/KLN89/kln89_page_cal.cxx
+++ b/src/Instrumentation/KLN89/kln89_page_cal.cxx
@@ -116,7 +116,7 @@ void KLN89CalPage::Update(double dt) {
 			if(!(_uLinePos == 3 && crsr && blink)) { _kln89->DrawText("--", 2, 13, 2); }
 		}
 		if(_alarmAnnotate && _alarmIn.hr() < 10) {
-            sprintf(buf, "%01i", _alarmIn.hr());
+            snprintf(buf, sizeof(buf), "%01i", _alarmIn.hr());
 			if(!(_uLinePos == 4 && crsr && blink)) { _kln89->DrawText((string)buf, 2, 11, 1); }
 			sprintf(buf, "%02i", _alarmIn.min());
 			if(!(_uLinePos == 5 && crsr && blink)) { _kln89->DrawText((string)buf, 2, 13, 1); }
diff --git a/src/Instrumentation/clock.cxx b/src/Instrumentation/clock.cxx
index fa1dfc9d0..21de13e22 100644
--- a/src/Instrumentation/clock.cxx
+++ b/src/Instrumentation/clock.cxx
@@ -114,11 +114,11 @@ Clock::update (double delta_time_sec)
     while (hour >= 24)
         hour -= 24;
 
-    sprintf(_indicated_string, "%02d:%02d:%02d", hour, min, sec);
+    snprintf(_indicated_string, sizeof(_indicated_string), "%02d:%02d:%02d", hour, min, sec);
     _string_node->setStringValue(_indicated_string);
-    sprintf(_indicated_short_string, "%02d:%02d", hour, min);
+    snprintf(_indicated_short_string, sizeof(_indicated_short_string), "%02d:%02d", hour, min);
     _string_node1->setStringValue(_indicated_short_string);
-    sprintf(_local_short_string, "%02d:%02d", lhour, min);
+    snprintf(_local_short_string, sizeof(_local_short_string), "%02d:%02d", lhour, min);
     _string_node2->setStringValue(_local_short_string);
     _is_serviceable = true;