diff --git a/src/math/polysat/slicing.cpp b/src/math/polysat/slicing.cpp
index 674804145..dcfba7d94 100644
--- a/src/math/polysat/slicing.cpp
+++ b/src/math/polysat/slicing.cpp
@@ -198,6 +198,7 @@ namespace polysat {
                 xs.push_back(x);
             }
         }
+        SASSERT(ys.empty());
     }
 
     void slicing::find_base(slice src, slice_vector& out_base) const {
diff --git a/src/math/polysat/slicing.h b/src/math/polysat/slicing.h
index 03320f2ba..bbe18ad5b 100644
--- a/src/math/polysat/slicing.h
+++ b/src/math/polysat/slicing.h
@@ -32,6 +32,8 @@ namespace polysat {
 
     class slicing final {
 
+        friend class test_slicing;
+
         // solver&     m_solver;
 
 #if 0
@@ -111,16 +113,16 @@ namespace polysat {
         // Retrieve (or create) base slices s_1,...,s_n such that src[hi:lo] == s_1 ++ ... ++ s_n
         void mk_slice(slice src, unsigned hi, unsigned lo, slice_vector& out_base);
 
-        // find representative
+        // Find representative
         slice_idx find(slice_idx i) const;
 
-        // merge equivalence classes of two base slices
+        // Merge equivalence classes of two base slices
         void merge(slice_idx s1, slice_idx s2);
 
-        // Equality x_1 ++ ... ++ x_n == y_1 ++ ... ++ y_k
+        // Merge equality x_1 ++ ... ++ x_n == y_1 ++ ... ++ y_k
         //
         // Precondition:
-        // - sequence of base slices without holes  (TODO: condition on holes probably not necessary? total widths have to match of course)
+        // - sequence of base slices (equal total width)
         // - ordered from msb to lsb
         // - slices have the same reference point
         void merge(slice_vector& xs, slice_vector& ys);
diff --git a/src/test/CMakeLists.txt b/src/test/CMakeLists.txt
index 27de8b3af..07a559365 100644
--- a/src/test/CMakeLists.txt
+++ b/src/test/CMakeLists.txt
@@ -109,6 +109,7 @@ add_executable(test-z3
   simple_parser.cpp
   simplex.cpp
   simplifier.cpp
+  slicing.cpp
   small_object_allocator.cpp
   smt2print_parse.cpp
   smt_context.cpp
diff --git a/src/test/main.cpp b/src/test/main.cpp
index bf839bd64..f222837a8 100644
--- a/src/test/main.cpp
+++ b/src/test/main.cpp
@@ -267,6 +267,7 @@ int main(int argc, char ** argv) {
     TST(fixplex);
     TST(mod_interval);
     TST(viable);
+    TST(slicing);
     TST(totalizer);
     TST(distribution);
 }
diff --git a/src/test/slicing.cpp b/src/test/slicing.cpp
new file mode 100644
index 000000000..b87b58651
--- /dev/null
+++ b/src/test/slicing.cpp
@@ -0,0 +1,15 @@
+#include "math/polysat/slicing.h"
+
+namespace polysat {
+
+    class test_slicing {
+
+    };
+
+}
+
+
+void tst_slicing() {
+    using namespace polysat;
+    std::cout << "ok\n";
+}