diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 5d0c3df13..9b19ac9e1 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -9183,6 +9183,9 @@ gb_internal ExprKind check_call_expr(CheckerContext *c, Operand *operand, Ast *c
 			gb_string_free(b);
 			gb_string_free(a);
 		}
+		if (is_arch_wasm() && !check_target_feature_is_enabled(str_lit("tail-call"), nullptr)) {
+			error(call, "'#must_tail' on a WebAssembly target requires the 'tail-call' target feature, e.g. '-target-features:tail-call'");
+		}
 		break;
 	}
 
diff --git a/src/llvm_abi.cpp b/src/llvm_abi.cpp
index 4af0fed0f..02da1c835 100644
--- a/src/llvm_abi.cpp
+++ b/src/llvm_abi.cpp
@@ -150,6 +150,15 @@ gb_internal LLVMTypeRef lb_function_type_to_llvm_raw(lbFunctionType *ft, bool is
 // 	return LLVMPointerType(func_type, 0);
 // }
 
+gb_internal lbCallingConventionKind lb_calling_convention_kind(ProcCallingConvention cc) {
+	if (selected_subtarget == Subtarget_Playdate) {
+		return lbCallingConvention_ARM_AAPCS_VFP;
+	}
+	if (is_arch_wasm()) {
+		return lbCallingConvention_C;
+	}
+	return lb_calling_convention_map[cc];
+}
 
 gb_internal void lb_add_function_type_attributes(LLVMValueRef fn, lbFunctionType *ft, ProcCallingConvention calling_convention) {
 	if (ft == nullptr) {
@@ -204,13 +213,7 @@ gb_internal void lb_add_function_type_attributes(LLVMValueRef fn, lbFunctionType
 		LLVMAddAttributeAtIndex(fn, offset, noalias_attr);
 	}
 
-	lbCallingConventionKind cc_kind = lbCallingConvention_C;
-	// TODO(bill): Clean up this logic
-	if (selected_subtarget == Subtarget_Playdate) {
-		cc_kind = lbCallingConvention_ARM_AAPCS_VFP;
-	} else if (!is_arch_wasm()) {
-		cc_kind = lb_calling_convention_map[calling_convention];
-	}
+	lbCallingConventionKind cc_kind = lb_calling_convention_kind(calling_convention);
 	// if (build_context.metrics.arch == TargetArch_amd64) {
 	// 	if (build_context.metrics.os == TargetOs_windows) {
 	// 		if (cc_kind == lbCallingConvention_C) {
diff --git a/src/llvm_backend.hpp b/src/llvm_backend.hpp
index 6e933d152..828566c38 100644
--- a/src/llvm_backend.hpp
+++ b/src/llvm_backend.hpp
@@ -718,6 +718,8 @@ lbCallingConventionKind const lb_calling_convention_map[ProcCC_MAX] = {
 
 };
 
+gb_internal lbCallingConventionKind lb_calling_convention_kind(ProcCallingConvention cc);
+
 enum : LLVMDWARFTypeEncoding {
 	LLVMDWARFTypeEncoding_Address = 1,
 	LLVMDWARFTypeEncoding_Boolean = 2,
diff --git a/src/llvm_backend_proc.cpp b/src/llvm_backend_proc.cpp
index 5b55bbf14..d5c066eb2 100644
--- a/src/llvm_backend_proc.cpp
+++ b/src/llvm_backend_proc.cpp
@@ -471,13 +471,7 @@ gb_internal lbProcedure *lb_create_dummy_procedure(lbModule *m, String link_name
 	p->value = LLVMAddFunction(m->mod, c_link_name, func_type);
 
 	Type *pt = p->type;
-	lbCallingConventionKind cc_kind = lbCallingConvention_C;
-	if (selected_subtarget == Subtarget_Playdate) {
-		cc_kind = lbCallingConvention_ARM_AAPCS_VFP;
-	} else if (!is_arch_wasm()) {
-		cc_kind = lb_calling_convention_map[pt->Proc.calling_convention];
-	}
-	LLVMSetFunctionCallConv(p->value, cc_kind);
+	LLVMSetFunctionCallConv(p->value, lb_calling_convention_kind(pt->Proc.calling_convention));
 	lbValue proc_value = {p->value, p->type};
 	lb_add_member(m, p->name, proc_value);
 	lb_add_procedure_value(m, p);
@@ -1074,11 +1068,7 @@ gb_internal lbValue lb_emit_call_internal(lbProcedure *p, lbValue value, lbValue
 
 		LLVMValueRef ret = LLVMBuildCall2(p->builder, fnp, fn, args, arg_count, "");
 
-		auto llvm_cc = lb_calling_convention_map[proc_type->Proc.calling_convention];
-		if (selected_subtarget == Subtarget_Playdate) {
-			llvm_cc = lbCallingConvention_ARM_AAPCS_VFP;
-		}
-		LLVMSetInstructionCallConv(ret, llvm_cc);
+		LLVMSetInstructionCallConv(ret, lb_calling_convention_kind(proc_type->Proc.calling_convention));
 
 		LLVMAttributeIndex param_offset = LLVMAttributeIndex_FirstArgIndex;
 		if (return_ptr.value != nullptr) {