diff --git a/bundles/org.eclipse.equinox.preferences/src/org/eclipse/core/internal/preferences/EclipsePreferences.java b/bundles/org.eclipse.equinox.preferences/src/org/eclipse/core/internal/preferences/EclipsePreferences.java
index a5eb8ad..e039a9b 100644
--- a/bundles/org.eclipse.equinox.preferences/src/org/eclipse/core/internal/preferences/EclipsePreferences.java
+++ b/bundles/org.eclipse.equinox.preferences/src/org/eclipse/core/internal/preferences/EclipsePreferences.java
@@ -1217,7 +1217,7 @@
 	}
 
 	public String toDeepDebugString() {
-		final StringBuffer buffer = new StringBuffer();
+		final StringBuilder buffer = new StringBuilder();
 		IPreferenceNodeVisitor visitor = (IEclipsePreferences node) -> {
 			buffer.append(node);
 			buffer.append('\n');
diff --git a/bundles/org.eclipse.equinox.security/src/org/eclipse/equinox/internal/security/storage/CryptoData.java b/bundles/org.eclipse.equinox.security/src/org/eclipse/equinox/internal/security/storage/CryptoData.java
index 4e9703b..c7e59a2 100644
--- a/bundles/org.eclipse.equinox.security/src/org/eclipse/equinox/internal/security/storage/CryptoData.java
+++ b/bundles/org.eclipse.equinox.security/src/org/eclipse/equinox/internal/security/storage/CryptoData.java
@@ -93,7 +93,7 @@
 
 	@Override
 	public String toString() {
-		StringBuffer encryptedText = (moduleID == null) ? new StringBuffer() : new StringBuffer(moduleID);
+		StringBuilder encryptedText = (moduleID == null) ? new StringBuilder() : new StringBuilder(moduleID);
 		encryptedText.append(MODULE_ID_SEPARATOR);
 		if (iv != null) {
 			encryptedText.append(Base64.encode(iv));