diff --git a/java-compiler-testing/src/main/java/io/github/ascopes/jct/compilers/impl/JavacJctFlagBuilderImpl.java b/java-compiler-testing/src/main/java/io/github/ascopes/jct/compilers/impl/JavacJctFlagBuilderImpl.java
index 2e49c3b68..f4c9ef279 100644
--- a/java-compiler-testing/src/main/java/io/github/ascopes/jct/compilers/impl/JavacJctFlagBuilderImpl.java
+++ b/java-compiler-testing/src/main/java/io/github/ascopes/jct/compilers/impl/JavacJctFlagBuilderImpl.java
@@ -122,7 +122,7 @@ public JavacJctFlagBuilderImpl target(@Nullable String version) {
   }
 
   @Override
-  public JctFlagBuilder debuggingInfo(Set<DebuggingInfo> set) {
+  public JavacJctFlagBuilderImpl debuggingInfo(Set<DebuggingInfo> set) {
     if (set.isEmpty()) {
       craftedFlags.add(DEBUG_NONE);
       return this;
@@ -144,7 +144,7 @@ public JctFlagBuilder debuggingInfo(Set<DebuggingInfo> set) {
   }
 
   @Override
-  public JctFlagBuilder parameterInfoEnabled(boolean enabled) {
+  public JavacJctFlagBuilderImpl parameterInfoEnabled(boolean enabled) {
     return addFlagIfTrue(enabled, PARAMETERS);
   }