diff --git a/pysuperconductor/os_gap_calc.py b/pysuperconductor/os_gap_calc.py
index 944ef96..7f46417 100644
--- a/pysuperconductor/os_gap_calc.py
+++ b/pysuperconductor/os_gap_calc.py
@@ -51,7 +51,9 @@ def find_gap(
 
 
 # this is n * Delta_0, calling it n in this file for brevity
-def n_integrand_function(xi, temp, delta, mu_star):
+def n_integrand_function(
+	xi: float, temp: float, delta: float, mu_star: float
+) -> float:
 	big_e = energy(xi, delta)
 	left = 1 / (1 + numpy.exp((big_e - mu_star) / temp))
 	right = 1 / (1 + numpy.exp(big_e / temp))
@@ -59,8 +61,8 @@ def n_integrand_function(xi, temp, delta, mu_star):
 
 
 # as above, this is brevity n * Delta_0
-def n_integral(temp, delta, mu_star):
-	def integrand(xi):
+def n_integral(temp: float, delta: float, mu_star: float) -> float:
+	def integrand(xi: float) -> float:
 		return n_integrand_function(xi, temp, delta, mu_star)
 	intermediate = 20 * numpy.sqrt(delta ** 2 + mu_star ** 2)
 	lower = integrate.quad(integrand, 0, intermediate)[0]