diff --git a/gw_eccentricity/eccDefinition.py b/gw_eccentricity/eccDefinition.py
index 16d80d2d..2813c038 100644
--- a/gw_eccentricity/eccDefinition.py
+++ b/gw_eccentricity/eccDefinition.py
@@ -584,6 +584,22 @@ def process_data_dict(self,
         amp22_merger = newDataDict["amplm"][(2, 2)][merger_idx]
         phase22 = newDataDict["phaselm"][(2, 2)]
         phase22_merger = phase22[merger_idx]
+        # check if phase22 is increasing. phase22 at merger should be greater
+        # than the phase22 at the start of the waveform
+        if phase22_merger < phase22[0]:
+            raise Exception(
+                f"phase22 = {phase22_merger} at the merger is < "
+                f"phase22 = {phase22[0]} at the start. The "
+                "phaselm should be related to hlm as "
+                "hlm = amplm * exp(- i phaselm) ensuring that "
+                "the phaselm is monotonically increasing for m > 0 modes."
+                "This might be fixed by changing the overall sign of "
+                "phase in the input `dataDict`")
+        # check that omega22 is positive by checking its value at the merger
+        omega22_merger = newDataDict["omegalm"][(2, 2)][merger_idx]
+        if omega22_merger < 0:
+            raise Exception(f"omega22 at merger is {omega22_merger} < 0. "
+                            "omega22 must be positive.")
         # Minimum width for peak finding function
         min_width_for_extrema = self.get_width_for_peak_finder_from_phase22(
             newDataDict["t"],
diff --git a/test/test_dataDict.py b/test/test_dataDict.py
index 132cd277..94a28334 100644
--- a/test/test_dataDict.py
+++ b/test/test_dataDict.py
@@ -130,9 +130,10 @@ def test_dataDict():
                 # To avoid exception for residual method since the data does
                 # not contain zeroecc data
                 continue
+            second_data_dict = copy.deepcopy(dataDict2)
             # use data_w_hlm as dataDict1
             compare_eccentricity_measurement(dataDict1=dataDict1_w_hlm,
-                                             dataDict2=dataDict2,
+                                             dataDict2=second_data_dict,
                                              method=method)
     # Now we repeat the same as above but adding hlm_zeroecc to both the data
     # dict.
@@ -162,13 +163,15 @@ def test_dataDict():
             {"omegalm_zeroecc": omegalm_zeroecc})
         # Loop over the different methods
         for method in available_methods:
+            second_data_dict = copy.deepcopy(dataDict2_w_hlm_zeroecc)
             compare_eccentricity_measurement(
                 dataDict1=dataDict1_w_hlm_zeroecc,
-                dataDict2=dataDict2_w_hlm_zeroecc,
+                dataDict2=second_data_dict,
                 method=method)
+            second_data_dict = copy.deepcopy(dataDict2_w_hlm_zeroecc_and_omegalm_zeroecc)
             compare_eccentricity_measurement(
                 dataDict1=dataDict1_w_hlm_zeroecc,
-                dataDict2=dataDict2_w_hlm_zeroecc_and_omegalm_zeroecc,
+                dataDict2=second_data_dict,
                 method=method)
     # This time instead of adding hlm_zeroecc, we add amplm_zeroecc and
     # phaselm_zeroecc to dataDict2, dataDict1 is the same as above.
@@ -193,11 +196,13 @@ def test_dataDict():
             {"omegalm_zeroecc": omegalm_zeroecc})
         # Loop over the different methods
         for method in available_methods:
+            second_data_dict = copy.deepcopy(dataDict2_w_amplm_and_phaselm_zeroecc)
             compare_eccentricity_measurement(
                 dataDict1=dataDict1_w_hlm_zeroecc,
-                dataDict2=dataDict2_w_amplm_and_phaselm_zeroecc,
+                dataDict2=second_data_dict,
                 method=method)
+            second_data_dict = copy.deepcopy(dataDict2_w_amplm_and_phaselm_and_omegalm_zeroecc)
             compare_eccentricity_measurement(
                 dataDict1=dataDict1_w_hlm_zeroecc,
-                dataDict2=dataDict2_w_amplm_and_phaselm_and_omegalm_zeroecc,
+                dataDict2=second_data_dict,
                 method=method)