diff --git a/ogcore/output_plots.py b/ogcore/output_plots.py
index ba0a362bf..99b43b45a 100644
--- a/ogcore/output_plots.py
+++ b/ogcore/output_plots.py
@@ -76,7 +76,7 @@ def plot_aggregates(
         assert reform_tpi is not None
     fig1, ax1 = plt.subplots()
     for i, v in enumerate(var_list):
-        assert v in VAR_LABELS.keys() #TODO provide warning message here
+        assert v in VAR_LABELS.keys(), "{} is not in the list of variable labels".format(v)
         if plot_type == "pct_diff":
             if v in ["r_gov", "r", "r_p"]:
                 # Compute just percentage point changes for rates
@@ -238,7 +238,7 @@ def plot_industry_aggregates(
         assert reform_tpi is not None
     fig1, ax1 = plt.subplots()
     for i, v in enumerate(var_list):
-        assert v in VAR_LABELS.keys() #TODO provide warning message here
+        assert v in VAR_LABELS.keys(), "{} is not in the list of variable labels".format(v)
         if len(var_list) == 1:
             var_label = ""
         else:
@@ -451,7 +451,7 @@ def plot_gdp_ratio(
     start_index = start_year - base_params.start_year
     fig1, ax1 = plt.subplots()
     for i, v in enumerate(var_list):
-        assert v in ToGDP_LABELS.keys() #TODO provide warning message here
+        assert v in ToGDP_LABELS.keys(), "{} is not in the list of variable labels".format(v)
         if plot_type == "levels":
             plot_var_base = (
                 base_tpi[v][: base_params.T] / base_tpi["Y"][: base_params.T]