diff --git a/bindings/c/include/manifold/manifoldc.h b/bindings/c/include/manifold/manifoldc.h
index 054f353a9..580b098dc 100644
--- a/bindings/c/include/manifold/manifoldc.h
+++ b/bindings/c/include/manifold/manifoldc.h
@@ -215,7 +215,7 @@ double manifold_min_gap(ManifoldManifold *m, ManifoldManifold *other,
                         double searchLength);
 ManifoldManifold *manifold_calculate_normals(void *mem, ManifoldManifold *m,
                                              int normal_idx,
-                                             int min_sharp_angle);
+                                             double min_sharp_angle);
 
 // CrossSection Shapes/Constructors
 ManifoldCrossSection *manifold_cross_section_empty(void *mem);
diff --git a/bindings/c/manifoldc.cpp b/bindings/c/manifoldc.cpp
index d4dbe3bff..ca40b344b 100644
--- a/bindings/c/manifoldc.cpp
+++ b/bindings/c/manifoldc.cpp
@@ -680,7 +680,7 @@ double manifold_min_gap(ManifoldManifold *m, ManifoldManifold *other,
 
 ManifoldManifold *manifold_calculate_normals(void *mem, ManifoldManifold *m,
                                              int normal_idx,
-                                             int min_sharp_angle) {
+                                             double min_sharp_angle) {
   auto man = from_c(m)->CalculateNormals(normal_idx, min_sharp_angle);
   return to_c(new (mem) Manifold(man));
 }