diff --git a/skimage/filters/lpi_filter.py b/skimage/filters/lpi_filter.py
index 36442eb9..e160407a 100644
--- a/skimage/filters/lpi_filter.py
+++ b/skimage/filters/lpi_filter.py
@@ -213,7 +213,7 @@ def wiener(data, impulse_response=None, filter_params={}, K=0.25,
     data : (M,N) ndarray
         Input data.
     K : float or (M,N) ndarray
-        Ratio between power spectrum of noise and undergraded
+        Ratio between power spectrum of noise and undegraded
         image.
     impulse_response : callable `f(r, c, **filter_params)`
         Impulse response of the filter.  See LPIFilter2D.__init__.
diff --git a/skimage/transform/finite_radon_transform.py b/skimage/transform/finite_radon_transform.py
index 9d3780b1..dd3bad33 100644
--- a/skimage/transform/finite_radon_transform.py
+++ b/skimage/transform/finite_radon_transform.py
@@ -29,7 +29,7 @@ def frt2(a):
 
     Notes
     -----
-    The FRT has a unique inverse if n is prime. [FRT]
+    The FRT has a unique inverse iff n is prime. [FRT]
     The idea for this algorithm is due to Vlad Negnevitski.
 
     Examples
@@ -88,7 +88,7 @@ def ifrt2(a):
 
     Notes
     -----
-    The FRT has a unique inverse if n is prime.
+    The FRT has a unique inverse iff n is prime.
     See [1]_ for an overview.
     The idea for this algorithm is due to Vlad Negnevitski.