diff --git a/notebooks/Test.ipynb b/notebooks/Test.ipynb
index ea85feac..6283e47e 100644
--- a/notebooks/Test.ipynb
+++ b/notebooks/Test.ipynb
@@ -13,6 +13,18 @@
       "%pylab is deprecated, use %matplotlib inline and import the required libraries.\n",
       "Populating the interactive namespace from numpy and matplotlib\n"
      ]
+    },
+    {
+     "ename": "ImportError",
+     "evalue": "/home/wolfman/miniconda3/lib/python3.12/site-packages/pyiga-0.1.0-py3.12-linux-x86_64.egg/pyiga/fast_assemble_cy.cpython-312-x86_64-linux-gnu.so: undefined symbol: _Z16fast_assemble_2dPFdmmPvES_mimidiiiiRSt6vectorImSaImEES5_RS2_IdSaIdEE",
+     "output_type": "error",
+     "traceback": [
+      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+      "\u001b[0;31mImportError\u001b[0m                               Traceback (most recent call last)",
+      "Cell \u001b[0;32mIn[1], line 5\u001b[0m\n\u001b[1;32m      3\u001b[0m \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;21;01mscipy\u001b[39;00m\u001b[38;5;21;01m.\u001b[39;00m\u001b[38;5;21;01msparse\u001b[39;00m \u001b[38;5;28;01mimport\u001b[39;00m coo_matrix, csr_matrix, csc_matrix, block_diag, identity, hstack\n\u001b[1;32m      4\u001b[0m \u001b[38;5;28;01mimport\u001b[39;00m \u001b[38;5;21;01mmatplotlib\u001b[39;00m\u001b[38;5;21;01m.\u001b[39;00m\u001b[38;5;21;01mpyplot\u001b[39;00m \u001b[38;5;28;01mas\u001b[39;00m \u001b[38;5;21;01mplt\u001b[39;00m\n\u001b[0;32m----> 5\u001b[0m \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;21;01mpyiga\u001b[39;00m \u001b[38;5;28;01mimport\u001b[39;00m assemble, bspline, vform, geometry, vis, solvers, utils, topology, algebra, quadrature\n\u001b[1;32m      6\u001b[0m \u001b[38;5;66;03m#from sksparse.cholmod import cholesky\u001b[39;00m\n\u001b[1;32m      7\u001b[0m \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;21;01mpyiga\u001b[39;00m \u001b[38;5;28;01mimport\u001b[39;00m adaptive \u001b[38;5;28;01mas\u001b[39;00m adap\n",
+      "File \u001b[0;32m~/miniconda3/lib/python3.12/site-packages/pyiga-0.1.0-py3.12-linux-x86_64.egg/pyiga/assemble.py:115\u001b[0m\n\u001b[1;32m    113\u001b[0m \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;21;01m.\u001b[39;00m \u001b[38;5;28;01mimport\u001b[39;00m assemble_tools\n\u001b[1;32m    114\u001b[0m \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;21;01m.\u001b[39;00m \u001b[38;5;28;01mimport\u001b[39;00m assemblers\n\u001b[0;32m--> 115\u001b[0m \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;21;01m.\u001b[39;00m \u001b[38;5;28;01mimport\u001b[39;00m fast_assemble_cy\n\u001b[1;32m    116\u001b[0m \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;21;01m.\u001b[39;00m \u001b[38;5;28;01mimport\u001b[39;00m tensor\n\u001b[1;32m    117\u001b[0m \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;21;01m.\u001b[39;00m \u001b[38;5;28;01mimport\u001b[39;00m operators\n",
+      "\u001b[0;31mImportError\u001b[0m: /home/wolfman/miniconda3/lib/python3.12/site-packages/pyiga-0.1.0-py3.12-linux-x86_64.egg/pyiga/fast_assemble_cy.cpython-312-x86_64-linux-gnu.so: undefined symbol: _Z16fast_assemble_2dPFdmmPvES_mimidiiiiRSt6vectorImSaImEES5_RS2_IdSaIdEE"
+     ]
     }
    ],
    "source": [
diff --git a/notebooks/multipatch.ipynb b/notebooks/multipatch.ipynb
index 1d850ae2..ef29c4ed 100755
--- a/notebooks/multipatch.ipynb
+++ b/notebooks/multipatch.ipynb
@@ -58,15 +58,15 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 5,
+   "execution_count": 4,
    "metadata": {},
    "outputs": [
     {
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "setting up constraints took 0.00635981559753418 seconds.\n",
-      "Basis setup took 0.0038449764251708984 seconds\n"
+      "setting up constraints took 0.006209373474121094 seconds.\n",
+      "Basis setup took 0.022143125534057617 seconds\n"
      ]
     },
     {
@@ -117,7 +117,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 6,
+   "execution_count": 5,
    "metadata": {},
    "outputs": [
     {
@@ -141,6 +141,13 @@
     "MP.plot(u, range = (0, 1.5e-1), cmap='viridis')"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  },
   {
    "cell_type": "code",
    "execution_count": null,
diff --git a/pyiga/fast_assemble_cy.pyx b/pyiga/fast_assemble_cy.pyx
index cc39a6f2..0a90a67e 100644
--- a/pyiga/fast_assemble_cy.pyx
+++ b/pyiga/fast_assemble_cy.pyx
@@ -32,7 +32,6 @@ cdef extern void fast_assemble_3d_cimpl "fast_assemble_3d"(
 #
 # Imports end
 #
-
 # this is so that IPython notebooks can capture the output
 cdef void _stdout_log_func(const char * s, size_t nbytes) noexcept:
     import sys
diff --git a/pyiga/fastasm.cc b/pyiga/fastasm.cc
index 687a3a07..cf936bea 100644
--- a/pyiga/fastasm.cc
+++ b/pyiga/fastasm.cc
@@ -55,7 +55,7 @@ void cout_logfunc(const char * str, size_t)
 FunctionStringBuf log_stringbuf(cout_logfunc);
 std::ostream logger(&log_stringbuf);
 
-extern "C" void set_log_func(LogFuncPtr logfunc)
+extern void set_log_func(LogFuncPtr logfunc)
 {
     if (logfunc)
         log_stringbuf.set_func(logfunc);
@@ -698,7 +698,7 @@ void inflate_3d(const Array3D<double>& X,
 // Main entry points
 ////////////////////////////////////////////////////////////////////////////////
 
-extern "C" void fast_assemble_2d(
+extern void fast_assemble_2d(
         // matrix specification
         MatrixEntryFn entryfunc,
         void * data,
@@ -728,7 +728,7 @@ extern "C" void fast_assemble_2d(
 }
 
 
-extern "C" void fast_assemble_3d(
+extern void fast_assemble_3d(
         // matrix specification
         MatrixEntryFn entryfunc,
         void * data,
@@ -757,4 +757,4 @@ extern "C" void fast_assemble_3d(
 
     inflate_3d(X, sparsidx0, sparsidx1, sparsidx2, block_sizes,
             entries_i, entries_j, entries);
-}
+}
\ No newline at end of file