diff --git a/basisu_tool.cpp b/basisu_tool.cpp
index 0123a76..8172a8c 100644
--- a/basisu_tool.cpp
+++ b/basisu_tool.cpp
@@ -84,7 +84,7 @@
 		" -normal_map: Tunes codec parameters for better quality on normal maps (linear colorspace metrics, linear mipmap filtering, no selector RDO, no sRGB)\n"
 		" -no_alpha: Always output non-alpha basis files, even if one or more inputs has alpha\n"
 		" -force_alpha: Always output alpha basis files, even if no inputs has alpha\n"
-		" -seperate_rg_to_color_alpha: Seperate input R and G channels to RGB and A (for tangent space XY normal maps)\n"
+		" -separate_rg_to_color_alpha: Separate input R and G channels to RGB and A (for tangent space XY normal maps)\n"
 		" -no_multithreading: Disable multithreading\n"
 		" -no_ktx: Disable KTX writing when unpacking (faster)\n"
 		" -etc1_only: Only unpack to ETC1, skipping the other texture formats during -unpack\n"
@@ -353,7 +353,8 @@
 				m_comp_params.m_check_for_alpha = false;
 			else if (strcasecmp(pArg, "-force_alpha") == 0)
 				m_comp_params.m_force_alpha = true;
-			else if (strcasecmp(pArg, "-seperate_rg_to_color_alpha") == 0)
+			else if ((strcasecmp(pArg, "-separate_rg_to_color_alpha") == 0) ||
+			        (strcasecmp(pArg, "-seperate_rg_to_color_alpha") == 0)) // was mispelled for a while - whoops!
 				m_comp_params.m_seperate_rg_to_color_alpha = true;
 			else if (strcasecmp(pArg, "-no_multithreading") == 0)
 			{