diff --git a/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop.desc b/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop.desc
index 85e229139945..f3210d67f829 100644
--- a/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop.desc
+++ b/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop.desc
@@ -1,4 +1,4 @@
-FUTURE
+CORE
 Test.class
 --refine-strings --string-max-length 1000 --string-max-input-length 100 --function Test.bufferNonDetLoop --depth 10000 --unwind 5  --verbosity 10  --property "java::Test.bufferNonDetLoop:(ILjava/lang/String;)Ljava/lang/String;.assertion.1"
 ^EXIT=10$
diff --git a/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop2.desc b/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop2.desc
index 8f2983e4c34c..63814912cda3 100644
--- a/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop2.desc
+++ b/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop2.desc
@@ -1,4 +1,4 @@
-FUTURE
+CORE
 Test.class
 --refine-strings --string-max-length 1000 --string-max-input-length 100 --function Test.bufferNonDetLoop2 --depth 10000 --unwind 5  --verbosity 10
 ^EXIT=10$
diff --git a/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop4.desc b/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop4.desc
index 6d2ad2eac223..19ccb17fdf28 100644
--- a/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop4.desc
+++ b/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop4.desc
@@ -1,4 +1,4 @@
-FUTURE
+CORE
 Test.class
 --refine-strings --string-max-length 1000 --string-max-input-length 100 --function Test.bufferNonDetLoop4 --depth 10000 --unwind 5  --verbosity 10 --property "java::Test.bufferNonDetLoop4:(IILjava/lang/String;)Ljava/lang/String;.assertion.1"
 ^EXIT=10$
diff --git a/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop5.desc b/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop5.desc
index 87c043ab6939..7022df3ff8dd 100644
--- a/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop5.desc
+++ b/regression/jbmc-strings/StringConcat/test_buffer_nondet_loop5.desc
@@ -1,6 +1,6 @@
-FUTURE
+CORE
 Test.class
---refine-strings --string-max-length 1000 --string-max-input-length 100 --function Test.bufferNonDetLoop5 --depth 10000 --unwind 5  --verbosity 10
+--refine-strings --string-max-length 1000 --string-max-input-length 100 --function Test.bufferNonDetLoop5 --depth 10000 --unwind 3 --verbosity 10
 ^EXIT=10$
 ^SIGNAL=0$
 ^VERIFICATION FAILED$
diff --git a/regression/jbmc-strings/StringConcat/test_string_nondet.desc b/regression/jbmc-strings/StringConcat/test_string_nondet.desc
index 14f7c8ae8d03..cfce92f3210d 100644
--- a/regression/jbmc-strings/StringConcat/test_string_nondet.desc
+++ b/regression/jbmc-strings/StringConcat/test_string_nondet.desc
@@ -1,4 +1,4 @@
-FUTURE
+CORE
 Test.class
 --refine-strings --string-max-length 1000 --string-max-input-length 100 --function Test.stringNonDet --depth 10000 --unwind 5 --verbosity 10
 ^EXIT=10$