diff --git a/.github/workflows/dnmtools_release_linux.yml b/.github/workflows/dnmtools_release_linux.yml
index d4f12f78..23bce442 100644
--- a/.github/workflows/dnmtools_release_linux.yml
+++ b/.github/workflows/dnmtools_release_linux.yml
@@ -59,7 +59,7 @@ jobs:
             cd /workspace && \
             autoreconf -i && \
             mkdir build && cd build && \
-            ../configure --with-libdeflate && \
+            ../configure --with-libdeflate --with-htsmods && \
             ../data/make_full_license_info_header.sh ../data/LICENSE > license.h && \
             echo "#define INCLUDE_FULL_LICENSE_INFO 1" >> config.h && \
             make -j4 LDFLAGS="-static-libgcc -static-libstdc++ -s" && \
diff --git a/.github/workflows/dnmtools_release_macos.yml b/.github/workflows/dnmtools_release_macos.yml
index 54f48513..eeca2b16 100644
--- a/.github/workflows/dnmtools_release_macos.yml
+++ b/.github/workflows/dnmtools_release_macos.yml
@@ -54,7 +54,7 @@ jobs:
         run: |
           ./autogen.sh
           mkdir build && cd build
-          ../configure --with-libdeflate \
+          ../configure --with-libdeflate --with-htsmods \
             CXX=g++-14 \
             LDFLAGS="-L/opt/dnmtools/lib -static-libgcc -static-libstdc++ -Wl,-dead_strip" \
             CPPFLAGS="-I/opt/dnmtools/include"
diff --git a/src/analysis/nanopore.cpp b/src/analysis/nanopore.cpp
index 0027e74a..e44b5ee5 100644
--- a/src/analysis/nanopore.cpp
+++ b/src/analysis/nanopore.cpp
@@ -942,14 +942,16 @@ valid_modification_types(const std::string &infile,
     // ADS: or bam_parse_basemod2(aln.b, m, HTS_MOD_REPORT_UNCHECKED)
     int n_types{};
     const auto types = bam_mods_recorded(m.get(), &n_types);
-    valid_types = (n_types == 1 && types[0] == 'C') ||
-                  (n_types >= 2 && types[0] == 'h' && types[1] == 'm');
+    // clang-format off
+    valid_types = ((n_types == 0) ||
+                   (n_types == 1 && types[0] == 'C') ||
+                   (n_types >= 2 && types[0] == 'h' && types[1] == 'm'));
+    // clang-format on
     if (!valid_types) {
       message = "n_types: " + std::to_string(n_types) + "\n";
-      for (auto i = 0; i < n_types; ++i) {
+      for (auto i = 0; i < n_types; ++i)
         message += "type[" + std::to_string(i) +
                    "]=" + std::to_string(static_cast<char>(types[i])) + "\n";
-      }
     }
   }
   return std::make_pair(valid_types, message);