diff --git a/vskernels/kernels/bicubic.py b/vskernels/kernels/bicubic.py
index a62bd90..d26798b 100644
--- a/vskernels/kernels/bicubic.py
+++ b/vskernels/kernels/bicubic.py
@@ -70,7 +70,9 @@ def get_params_args(
 
     @inject_self.property
     def kernel_size(self) -> int:
-        return 1 + ((self.b, self.c) != (0, 0))
+        if (self.b, self.c) == (0, 0):
+            return 1
+        return 2
 
 
 class BSpline(Bicubic):
diff --git a/vskernels/kernels/placebo.py b/vskernels/kernels/placebo.py
index 8c44dfa..c9ada32 100644
--- a/vskernels/kernels/placebo.py
+++ b/vskernels/kernels/placebo.py
@@ -84,15 +84,14 @@ def get_params_args(
             lut_entries=self.lut_entries, trc=curve.value_libplacebo
         )
 
-    def _kernel_size(self, taps: float | None = None, b: float | None = None, c: float | None = None) -> int:
-        if taps:
-            return ceil(taps)
+    @inject_self.property
+    def kernel_size(self) -> int:
+        from .bicubic import Bicubic
 
-        if b or c:
-            return 1 + ((fallback(b, 0), fallback(c, 0.5)) != (0, 0))
+        if self.taps:
+            return ceil(self.taps)
 
-        return 1
+        if self.b or self.c:
+            return Bicubic(self.b, self.c).kernel_size
 
-    @inject_self.property
-    def kernel_size(self) -> int:
-        return self._kernel_size(self.taps, self.b, self.c)
+        return 1