diff --git a/src/BPM/bond_bpm_rotational.cpp b/src/BPM/bond_bpm_rotational.cpp
index aba3709dc9..71b1165f39 100644
--- a/src/BPM/bond_bpm_rotational.cpp
+++ b/src/BPM/bond_bpm_rotational.cpp
@@ -296,7 +296,7 @@ double BondBPMRotational::elastic_forces(int i1, int i2, int type, double r_mag,
   c = q21[0] * q21[0] - q21[1] * q21[1] - q21[2] * q21[2] + q21[3] * q21[3];
   theta = acos_limit(c);
 
-  // Separately calculte magnitude of quaternion in x-y and out of x-y planes
+  // Separately calculate magnitude of quaternion in x-y and out of x-y planes
   // to avoid dividing by zero
   mag_out_plane = (q21[0] * q21[0] + q21[3] * q21[3]);
   mag_in_plane = (q21[1] * q21[1] + q21[2] * q21[2]);