diff --git a/src/test/scala/leon/test/verification/NewSolversRegression.scala b/src/test/scala/leon/test/verification/NewSolversRegression.scala
index 7329709b2e3715eba43cd97ec13b5113c31d574f..d7793a3b14bbd598eab94a47906fa77d0bd675b8 100644
--- a/src/test/scala/leon/test/verification/NewSolversRegression.scala
+++ b/src/test/scala/leon/test/verification/NewSolversRegression.scala
@@ -18,7 +18,7 @@ class NewSolversRegression extends VerificationRegression {
   val optionVariants: List[List[String]] = {
 
     val isCVC4Available = try {
-      CVC4Interpreter.buildDefault
+      CVC4Interpreter.buildDefault.free()
       true
     } catch {
       case e: java.io.IOException =>
diff --git a/src/test/scala/leon/test/verification/PureScalaVerificationRegression.scala b/src/test/scala/leon/test/verification/PureScalaVerificationRegression.scala
index 0221488a5886cd885e84ae175fef6dea9c76fb3d..3bd1b82d4936b1c31c97eff4b3bbb66449a8ad57 100644
--- a/src/test/scala/leon/test/verification/PureScalaVerificationRegression.scala
+++ b/src/test/scala/leon/test/verification/PureScalaVerificationRegression.scala
@@ -16,7 +16,7 @@ class PureScalaVerificationRegression extends VerificationRegression {
   val pipeBack = AnalysisPhase
   val optionVariants: List[List[String]] = {
     val isZ3Available = try {
-      Z3Interpreter.buildDefault
+      Z3Interpreter.buildDefault.free()
       true
     } catch {
       case e: java.io.IOException =>
@@ -24,7 +24,7 @@ class PureScalaVerificationRegression extends VerificationRegression {
     }
 
     val isCVC4Available = try {
-      CVC4Interpreter.buildDefault
+      CVC4Interpreter.buildDefault.free()
       true
     } catch {
       case e: java.io.IOException =>