diff --git a/common/src/main/kotlin/org/imdc/extensions/common/PyDatasetBuilder.kt b/common/src/main/kotlin/org/imdc/extensions/common/PyDatasetBuilder.kt
index 2d98097..bcc6155 100644
--- a/common/src/main/kotlin/org/imdc/extensions/common/PyDatasetBuilder.kt
+++ b/common/src/main/kotlin/org/imdc/extensions/common/PyDatasetBuilder.kt
@@ -22,7 +22,11 @@ class PyDatasetBuilder(private val builder: DatasetBuilder) : PyObject() {
     }
 
     fun colTypes(vararg types: PyObject) = apply {
-        builder.colTypes(types.map { it.asJavaClass() })
+        if (types.singleOrNull()?.isSequenceType == true) {
+            builder.colTypes(types.first().asIterable().map { it.asJavaClass() })
+        } else {
+            builder.colTypes(types.map { it.asJavaClass() })
+        }
     }
 
     fun colTypes(types: List<Class<*>>) = apply {
diff --git a/common/src/test/kotlin/org/imdc/extensions/common/DatasetExtensionsTests.kt b/common/src/test/kotlin/org/imdc/extensions/common/DatasetExtensionsTests.kt
index 0c7d07f..2cda029 100644
--- a/common/src/test/kotlin/org/imdc/extensions/common/DatasetExtensionsTests.kt
+++ b/common/src/test/kotlin/org/imdc/extensions/common/DatasetExtensionsTests.kt
@@ -16,6 +16,7 @@ import kotlin.io.path.writeBytes
 class DatasetExtensionsTests : JythonTest(
     { globals ->
         globals["utils"] = DatasetExtensions
+        globals["builder"] = DatasetBuilder.newBuilder()
         globals["dataset"] = DatasetBuilder.newBuilder()
             .colNames("a", "b", "c")
             .colTypes(Int::class.javaObjectType, Double::class.javaObjectType, String::class.java)
@@ -540,6 +541,16 @@ class DatasetExtensionsTests : JythonTest(
                     )
                 }
             }
+
+            test("Column types regression (issue #24)") {
+                eval<Dataset>(
+                    """
+                        builder.colNames(dataset.columnNames) \
+                            .colTypes(dataset.columnTypes) \
+                            .build()
+                    """.trimIndent(),
+                )
+            }
         }
     }
 }