diff --git a/sndlock.cpp b/sndlock.cpp
index aeb09f7..95606f6 100644
--- a/sndlock.cpp
+++ b/sndlock.cpp
@@ -475,7 +475,7 @@ int main(int argc, char* argv[])
                 lpf_bandwidth[i] = lpf_bandwidth_l;
                 sprintf(str, "principal angle##%d", i);
                 float principal_angle_l = principal_angle[i];
-                ImGui::SliderFloat(str, &principal_angle_l, 0.0f, M_PI/2.0f);
+                ImGui::SliderFloat(str, &principal_angle_l, 0.0f, M_PI);
                 principal_angle[i] = principal_angle_l;
 
                 ImGui::AlignTextToFramePadding();