diff --git a/src/main/java/org/inferred/freebuilder/processor/excerpt/CheckedBiMap.java b/src/main/java/org/inferred/freebuilder/processor/excerpt/CheckedBiMap.java
index 6e6d678f..71731dc2 100644
--- a/src/main/java/org/inferred/freebuilder/processor/excerpt/CheckedBiMap.java
+++ b/src/main/java/org/inferred/freebuilder/processor/excerpt/CheckedBiMap.java
@@ -50,9 +50,8 @@ public void addTo(SourceBuilder code) {
         .addLine("  @Override public V put(K key, V value) {")
         .addLine("    K oldKey = biMap.inverse().get(value);")
         .addLine("    %s.checkArgument(", Preconditions.class)
-        .addLine("        oldKey == null || %s.equals(oldKey, key),"
-                + " \"value already present: %%s\", value);",
-            Objects.class)
+        .addLine("        oldKey == null || %s.equals(oldKey, key),", Objects.class)
+        .addLine("        \"value already present: %%s\", value);")
         .addLine("    V oldValue = biMap.get(key);")
         .addLine("    forcePut.accept(key, value);")
         .addLine("    return oldValue;")
@@ -131,9 +130,8 @@ public void addTo(SourceBuilder code) {
           .addLine("  @Override public V setValue(V value) {")
           .addLine("    K oldKey = biMap.inverse().get(value);")
           .addLine("    %s.checkArgument(", Preconditions.class)
-          .addLine("        oldKey == null || %s.equals(oldKey, key),"
-                  + " \"value already present: %%s\", value);",
-              Objects.class)
+          .addLine("        oldKey == null || %s.equals(oldKey, key),", Objects.class)
+          .addLine("        \"value already present: %%s\", value);")
           .addLine("    V oldValue = this.value;")
           .addLine("    this.value = %s.requireNonNull(value);", Objects.class)
           .addLine("    forcePut.accept(key, value);")
diff --git a/src/main/java/org/inferred/freebuilder/processor/property/BiMapProperty.java b/src/main/java/org/inferred/freebuilder/processor/property/BiMapProperty.java
index 438168f7..5fdf61c7 100644
--- a/src/main/java/org/inferred/freebuilder/processor/property/BiMapProperty.java
+++ b/src/main/java/org/inferred/freebuilder/processor/property/BiMapProperty.java
@@ -228,9 +228,8 @@ private void addPut(SourceBuilder code) {
         unboxedValueType.orElse(valueType));
     code.addLine("  %s oldKey = %s.inverse().get(value);", keyType, property.getField())
         .addLine("  %s.checkArgument(", Preconditions.class)
-        .addLine("      oldKey == null || %s.equals(oldKey, key),"
-                + " \"value already present: %%s\", value);",
-            Objects.class)
+        .addLine("      oldKey == null || %s.equals(oldKey, key),", Objects.class)
+        .addLine("      \"value already present: %%s\", value);")
         .addLine("  %s(key, value);", forcePutMethod(property))
         .addLine("  return (%s) this;", datatype.getBuilder())
         .addLine("}");