diff --git a/src/algebra/TinyMatrix.hpp b/src/algebra/TinyMatrix.hpp
index f4c66232816b33d8ee7e8ac897436507181d5644..e34f98ed8c25df7a77ba90bbd7cd05305b5eb115 100644
--- a/src/algebra/TinyMatrix.hpp
+++ b/src/algebra/TinyMatrix.hpp
@@ -150,11 +150,14 @@ class [[nodiscard]] TinyMatrix
   {
     os << '[';
     for (size_t i = 0; i < M; ++i) {
-      os << '(' << NaNHelper(A(i, 0));
+      if (i > 0) {
+        os << ',';
+      }
+      os << '[' << NaNHelper(A(i, 0));
       for (size_t j = 1; j < N; ++j) {
         os << ',' << NaNHelper(A(i, j));
       }
-      os << ')';
+      os << ']';
     }
     os << ']';
 
diff --git a/src/algebra/TinyVector.hpp b/src/algebra/TinyVector.hpp
index 3ca3d2a38550b5a31bb16843d25a35cebdb10fd0..ae616a4849d0e681bf09e613ad4d19263d0f035a 100644
--- a/src/algebra/TinyVector.hpp
+++ b/src/algebra/TinyVector.hpp
@@ -100,11 +100,11 @@ class [[nodiscard]] TinyVector
   PUGS_INLINE
   constexpr friend std::ostream& operator<<(std::ostream& os, const TinyVector& v)
   {
-    os << '(' << NaNHelper(v.m_values[0]);
+    os << '[' << NaNHelper(v.m_values[0]);
     for (size_t i = 1; i < N; ++i) {
       os << ',' << NaNHelper(v.m_values[i]);
     }
-    os << ')';
+    os << ']';
     return os;
   }
 
diff --git a/tests/test_BinaryExpressionProcessor_shift.cpp b/tests/test_BinaryExpressionProcessor_shift.cpp
index 127e90161416444f652c16206ddbd8c4f97d5718..834e86cfe483d3745c483defc14d810809ffcd0b 100644
--- a/tests/test_BinaryExpressionProcessor_shift.cpp
+++ b/tests/test_BinaryExpressionProcessor_shift.cpp
@@ -130,22 +130,22 @@ fout << createSocketServer(0) << "\n";)";
       REQUIRE(std::string_view(line) == "(2.3, 4)");
 
       fin.getline(line, 1023);
-      REQUIRE(std::string_view(line) == "((2.3), (4))");
+      REQUIRE(std::string_view(line) == "([2.3], [4])");
 
       fin.getline(line, 1023);
-      REQUIRE(std::string_view(line) == "((2.3,4), (3,2))");
+      REQUIRE(std::string_view(line) == "([2.3,4], [3,2])");
 
       fin.getline(line, 1023);
-      REQUIRE(std::string_view(line) == "((2.3,4,-1), (3,2,1))");
+      REQUIRE(std::string_view(line) == "([2.3,4,-1], [3,2,1])");
 
       fin.getline(line, 1023);
-      REQUIRE(std::string_view(line) == "([(2.3)], [(4)])");
+      REQUIRE(std::string_view(line) == "([[2.3]], [[4]])");
 
       fin.getline(line, 1023);
-      REQUIRE(std::string_view(line) == "([(2.3,4)(2,0.3)], [(3,2.3)(1,-4)])");
+      REQUIRE(std::string_view(line) == "([[2.3,4],[2,0.3]], [[3,2.3],[1,-4]])");
 
       fin.getline(line, 1023);
-      REQUIRE(std::string_view(line) == "([(2.3,4,-1)(2,7,2.3)(6,2,8)], [(3,2,1)(1,2,5)(2.1,3,-2.6)])");
+      REQUIRE(std::string_view(line) == "([[2.3,4,-1],[2,7,2.3],[6,2,8]], [[3,2,1],[1,2,5],[2.1,3,-2.6]])");
 
       fin.getline(line, 1023);
       REQUIRE(std::string_view(line) == "(foo, bar)");
diff --git a/tests/test_TinyMatrix.cpp b/tests/test_TinyMatrix.cpp
index 81c187dc2f5c7663fb7491cfa5c68fc2fc2d7eb6..2f4c09d4ad9ce1dbb5e3d856d8737d27344459f2 100644
--- a/tests/test_TinyMatrix.cpp
+++ b/tests/test_TinyMatrix.cpp
@@ -272,8 +272,8 @@ TEST_CASE("TinyMatrix", "[algebra]")
 
   SECTION("checking for matrices output")
   {
-    REQUIRE(Catch::Detail::stringify(A) == "[(1,2,3,4)(5,6,7,8)(9,10,11,12)]");
-    REQUIRE(Catch::Detail::stringify(TinyMatrix<1, 1, int>(7)) == "[(7)]");
+    REQUIRE(Catch::Detail::stringify(A) == "[[1,2,3,4],[5,6,7,8],[9,10,11,12]]");
+    REQUIRE(Catch::Detail::stringify(TinyMatrix<1, 1, int>(7)) == "[[7]]");
   }
 
 #ifndef NDEBUG
@@ -287,7 +287,7 @@ TEST_CASE("TinyMatrix", "[algebra]")
     A_ost << A;
 
     std::ostringstream ref_ost;
-    ref_ost << "[(1,nan,3)(2,nan,nan)]";
+    ref_ost << "[[1,nan,3],[2,nan,nan]]";
 
     REQUIRE(A_ost.str() == ref_ost.str());
   }
diff --git a/tests/test_TinyVector.cpp b/tests/test_TinyVector.cpp
index 0613e721cbce46386e6b1c86c3bc3e1123fdd1aa..9c4dc2e5a2c4b185904fcf04a706fa70b572a197 100644
--- a/tests/test_TinyVector.cpp
+++ b/tests/test_TinyVector.cpp
@@ -30,7 +30,7 @@ TEST_CASE("TinyVector", "[algebra]")
   REQUIRE(((z[0] == 0) and (z[1] == 0) and (z[2] == 0)));
 
   v = TinyVector<3, int>(3, 2, 4);
-  REQUIRE(Catch::Detail::stringify(v) == "(3,2,4)");
+  REQUIRE(Catch::Detail::stringify(v) == "[3,2,4]");
 
   TinyVector<3, int> w(1, 2, 6);
   REQUIRE(dot(v, w) == 31);
@@ -96,7 +96,7 @@ TEST_CASE("TinyVector", "[algebra]")
     x_ost << x;
 
     std::ostringstream ref_ost;
-    ref_ost << "(nan,1,nan)";
+    ref_ost << "[nan,1,nan]";
 
     REQUIRE(x_ost.str() == ref_ost.str());
   }