diff --git a/movement_primitives/utils.py b/movement_primitives/utils.py
index 04ddec2..469ec53 100644
--- a/movement_primitives/utils.py
+++ b/movement_primitives/utils.py
@@ -2,10 +2,34 @@
 
 
 def ensure_1d_array(value, n_dims, var_name):
-    """Process scalar or array-like input to ensure it is a 1D numpy array of the correct shape."""
-    value = np.atleast_1d(value).astype(float).flatten()
-    if value.shape[0] == 1:
-        value = value * np.ones(n_dims)
-    elif value.shape != (n_dims,):
-        raise ValueError(f"{var_name} has incorrect shape, expected ({n_dims},) got {value.shape}")
+    """Process scalar or array-like input to ensure it is a 1D numpy array.
+
+    Parameters
+    ----------
+    value : float or array-like, shape (n_dims,)
+        Argument to be processed.
+
+    n_dims : int
+        Expected length of the 1d array.
+
+    var_name : str
+        Name of the variable in case an exception has to be raised.
+
+    Returns
+    -------
+    value : array, shape (n_dims,)
+        1D numpy array with dtype float.
+
+    Raises
+    ------
+    ValueError
+        If the argument is not compatible.
+    """
+    value = np.atleast_1d(value).astype(float)
+    if value.ndim == 1 and value.shape[0] == 1:
+        value = np.repeat(value, n_dims)
+    if value.ndim > 1 or value.shape[0] != n_dims:
+        raise ValueError(
+            f"{var_name} has incorrect shape, expected ({n_dims},) "
+            f"got {value.shape}")
     return value
diff --git a/test/test_utils.py b/test/test_utils.py
new file mode 100644
index 0000000..af776a5
--- /dev/null
+++ b/test/test_utils.py
@@ -0,0 +1,30 @@
+import numpy as np
+import pytest
+
+from movement_primitives.utils import ensure_1d_array
+
+
+def test_ensure_1d_array_float():
+    a = ensure_1d_array(5.0, 6, "a")
+    assert a.ndim == 1
+    assert a.shape[0] == 6
+
+
+def test_ensure_1d_array():
+    a = ensure_1d_array(np.ones(7), 7, "a")
+    assert a.ndim == 1
+    assert a.shape[0] == 7
+
+
+def test_ensure_1d_array_wrong_size():
+    with pytest.raises(
+            ValueError,
+            match=r"a has incorrect shape, expected \(8,\) got \(7,\)"):
+        ensure_1d_array(np.ones(7), 8, "a")
+
+
+def test_ensure_1d_array_wrong_shape():
+    with pytest.raises(
+            ValueError,
+            match=r"a has incorrect shape, expected \(7,\) got \(1, 7\)"):
+        ensure_1d_array(np.ones((1, 7)), 7, "a")