diff --git a/matrix.go b/matrix.go
index 2d3a3fd..2d80aeb 100644
--- a/matrix.go
+++ b/matrix.go
@@ -159,7 +159,8 @@ const MatrixEmulatorENV = "MATRIX_EMULATOR"
 func stringsToC(s []string) **C.char {
 	cArray := C.malloc(C.size_t(len(s)) * C.size_t(unsafe.Sizeof(uintptr(0))))
 
-	a := (*[len(s) - 1]*C.char)(cArray)
+	arglen := len(s) - 1
+	a := (*[arglen]*C.char)(cArray)
 
 	for idx, substring := range s {
 		a[idx] = C.CString(substring)