diff --git a/src/Reactor/LLVMReactor.cpp b/src/Reactor/LLVMReactor.cpp
index d3fd354..5a3f5f6 100644
--- a/src/Reactor/LLVMReactor.cpp
+++ b/src/Reactor/LLVMReactor.cpp
@@ -558,6 +558,7 @@
 			func_.emplace("cosf", reinterpret_cast<void*>(cosf));
 			func_.emplace("asinf", reinterpret_cast<void*>(asinf));
 			func_.emplace("acosf", reinterpret_cast<void*>(acosf));
+			func_.emplace("atanf", reinterpret_cast<void*>(atanf));
 
 #ifdef __APPLE__
 			// LLVM uses this function on macOS for tan.
@@ -3114,6 +3115,11 @@
 		return TransformFloat4PerElement(v, "acosf");
 	}
 
+	RValue<Float4> Atan(RValue<Float4> v)
+	{
+		return TransformFloat4PerElement(v, "atanf");
+	}
+
 	Type *Float4::getType()
 	{
 		return T(llvm::VectorType::get(T(Float::getType()), 4));