diff --git a/doc/utils/sphinx-config/false_positives.txt b/doc/utils/sphinx-config/false_positives.txt
index b776b7281b..463b2467fc 100644
--- a/doc/utils/sphinx-config/false_positives.txt
+++ b/doc/utils/sphinx-config/false_positives.txt
@@ -2979,6 +2979,8 @@ Subclassed
 subcutoff
 subcycle
 subcycling
+subhi
+sublo
 Subramaniyan
 subscripted
 subscripting
diff --git a/src/library.cpp b/src/library.cpp
index 0a8e70bc95..67fb51325f 100644
--- a/src/library.cpp
+++ b/src/library.cpp
@@ -995,6 +995,10 @@ int lammps_extract_global_datatype(void *handle, const char *name)
 
   if (strcmp(name,"boxlo") == 0) return LAMMPS_DOUBLE;
   if (strcmp(name,"boxhi") == 0) return LAMMPS_DOUBLE;
+  if (strcmp(name,"sublo") == 0) return LAMMPS_DOUBLE;
+  if (strcmp(name,"subhi") == 0) return LAMMPS_DOUBLE;
+  if (strcmp(name,"sublo_lambda") == 0) return LAMMPS_DOUBLE;
+  if (strcmp(name,"subhi_lambda") == 0) return LAMMPS_DOUBLE;
   if (strcmp(name,"boxxlo") == 0) return LAMMPS_DOUBLE;
   if (strcmp(name,"boxxhi") == 0) return LAMMPS_DOUBLE;
   if (strcmp(name,"boxylo") == 0) return LAMMPS_DOUBLE;
@@ -1159,6 +1163,22 @@ report the "native" data type.  The following tables are provided:
      - double
      - 1
      - upper box boundary in z-direction. See :doc:`create_box`.
+   * - sublo
+     - double
+     - 3
+     - subbox lower boundaries
+   * - subhi
+     - double
+     - 3
+     - subbox upper boundaries
+   * - sublo_lambda
+     - double
+     - 3
+     - subbox lower boundaries in fractional coordinates (for triclinic cells)
+   * - subhi_lambda
+     - double
+     - 3
+     - subbox upper boundaries in fractional coordinates (for triclinic cells)
    * - periodicity
      - int
      - 3
@@ -1352,6 +1372,8 @@ void *lammps_extract_global(void *handle, const char *name)
   if (strcmp(name,"boxhi") == 0) return (void *) lmp->domain->boxhi;
   if (strcmp(name,"sublo") == 0) return (void *) lmp->domain->sublo;
   if (strcmp(name,"subhi") == 0) return (void *) lmp->domain->subhi;
+  if (strcmp(name,"sublo_lambda") == 0) return (void *) lmp->domain->sublo_lamda;
+  if (strcmp(name,"subhi_lambda") == 0) return (void *) lmp->domain->subhi_lamda;
   if (strcmp(name,"boxxlo") == 0) return (void *) &lmp->domain->boxlo[0];
   if (strcmp(name,"boxxhi") == 0) return (void *) &lmp->domain->boxhi[0];
   if (strcmp(name,"boxylo") == 0) return (void *) &lmp->domain->boxlo[1];
diff --git a/unittest/c-library/test_library_mpi.cpp b/unittest/c-library/test_library_mpi.cpp
index 7936ee45ad..cf33ed13b5 100644
--- a/unittest/c-library/test_library_mpi.cpp
+++ b/unittest/c-library/test_library_mpi.cpp
@@ -110,6 +110,22 @@ TEST(MPI, sub_box)
     EXPECT_LE(subhi[1], boxhi[1]);
     EXPECT_LE(subhi[2], boxhi[2]);
 
+    ::testing::internal::CaptureStdout();
+    lammps_command(lmp, "change_box all triclinic");
+    ::testing::internal::GetCapturedStdout();
+
+    sublo = (double *)lammps_extract_global(lmp, "sublo_lambda");
+    subhi = (double *)lammps_extract_global(lmp, "subhi_lambda");
+    ASSERT_NE(sublo, nullptr);
+    ASSERT_NE(subhi, nullptr);
+
+    EXPECT_GE(sublo[0], 0.0);
+    EXPECT_GE(sublo[1], 0.0);
+    EXPECT_GE(sublo[2], 0.0);
+    EXPECT_LE(subhi[0], 1.0);
+    EXPECT_LE(subhi[1], 1.0);
+    EXPECT_LE(subhi[2], 1.0);
+
     ::testing::internal::CaptureStdout();
     lammps_close(lmp);
     ::testing::internal::GetCapturedStdout();