diff --git a/main/apiplugins/io.sarl.core/src/io/sarl/core/bic.sarl b/main/apiplugins/io.sarl.core/src/io/sarl/core/bic.sarl
index 6620c7253a..658750eb48 100644
--- a/main/apiplugins/io.sarl.core/src/io/sarl/core/bic.sarl
+++ b/main/apiplugins/io.sarl.core/src/io/sarl/core/bic.sarl
@@ -1021,9 +1021,9 @@ capacity Logging {
 
 	/** Set the logging level.
 	 *
-	 * @param level <code>0</code> for no logging, <code>1</code> for error,
+	 * @param level <code>0</code> or lower for no logging, <code>1</code> for error,
 	 *         <code>2</code> for warning, <code>3</code> for info,
-	 *         <code>5</code> for debug.
+	 *         <code>4</code> or higher for debug.
 	 */
 	def setLogLevel(level : int)
 
diff --git a/main/coreplugins/io.sarl.lang.core/src/io/sarl/lang/core/Skill.java b/main/coreplugins/io.sarl.lang.core/src/io/sarl/lang/core/Skill.java
index 22474beadf..710f09c79b 100644
--- a/main/coreplugins/io.sarl.lang.core/src/io/sarl/lang/core/Skill.java
+++ b/main/coreplugins/io.sarl.lang.core/src/io/sarl/lang/core/Skill.java
@@ -83,7 +83,7 @@ protected AgentTrait getCaller() {
 	 */
 	void registerUse() {
 		final int value = this.uses.getAndIncrement();
-		if (value <= 0) {
+		if (value == 0) {
 			install();
 		}
 	}
@@ -92,7 +92,7 @@ void registerUse() {
 	 */
 	void unregisterUse() {
 		final int value = this.uses.decrementAndGet();
-		if (value <= 0) {
+		if (value == 0) {
 			uninstall(UninstallationStage.PRE_DESTROY_EVENT);
 			uninstall(UninstallationStage.POST_DESTROY_EVENT);
 		}