diff --git a/q2_katharoseq/_methods.py b/q2_katharoseq/_methods.py
index 5bd63ca..4fbefa0 100644
--- a/q2_katharoseq/_methods.py
+++ b/q2_katharoseq/_methods.py
@@ -156,7 +156,7 @@ def estimating_biomass(
         positive_control_column: qiime2.CategoricalMetadataColumn,
         pcr_template_vol: int,
         dna_extract_vol: int,
-        extraction_mass_g: qiime2.CategoricalMetadataColumn) -> pd.DataFrame:
+        extraction_mass_g: qiime2.NumericMetadataColumn) -> pd.DataFrame:
 
     total_reads = total_reads.to_series()
     filtered = pd.DataFrame(total_reads[total_reads > min_total_reads])
diff --git a/q2_katharoseq/tests/support_files/input_estimating_biomass.tsv b/q2_katharoseq/tests/support_files/input_estimating_biomass.tsv
index b58cd50..3453c7f 100644
--- a/q2_katharoseq/tests/support_files/input_estimating_biomass.tsv
+++ b/q2_katharoseq/tests/support_files/input_estimating_biomass.tsv
@@ -1,5 +1,5 @@
 sample_name	total_reads	control_cell_into_extraction	extraction_mass_g	positive_control
-#q2:types	numeric	numeric	categorical	categorical
+#q2:types	numeric	numeric	numeric	categorical
 13414.plate1.h9	4			False
 13414.plate1.b10	6			False
 13414.plate1.e12	6			False