diff --git a/repos/spack_repo/builtin/packages/iperf3/package.py b/repos/spack_repo/builtin/packages/iperf3/package.py
index 1d0507fcae3..202e831a12f 100644
--- a/repos/spack_repo/builtin/packages/iperf3/package.py
+++ b/repos/spack_repo/builtin/packages/iperf3/package.py
@@ -17,6 +17,11 @@ class Iperf3(AutotoolsPackage):
 
     license("BSD-3-Clause-LBNL")
 
+    version("3.21", sha256="656e4405ebd620121de7ceca3eaf43a88f79ea1b857d041a6a0b1314801acdd8")
+    version("3.20", sha256="3acc572d1ecca4e0b20359c7bf0132ddc80d982efeee20c86f6726a9a6094388")
+    version("3.19.1", sha256="dc63f89ec581ea99f8b558d8eb35109de06383010db5a1906c208a562ba0c270")
+    version("3.19", sha256="040161da1555ec7411a9d81191049830ef37717d429a94ee6cf0842618e0e29c")
+    version("3.18", sha256="c0618175514331e766522500e20c94bfb293b4424eb27d7207fb427b88d20bab")
     version("3.17.1", sha256="84404ca8431b595e86c473d8f23d8bb102810001f15feaf610effd3b318788aa")
     version("3.17", sha256="077ede831b11b733ecf8b273abd97f9630fd7448d3ec1eaa789f396d82c8c943")
     version("3.16", sha256="cc740c6bbea104398cc3e466befc515a25896ec85e44a662d5f4a767b9cf713e")
@@ -26,3 +31,5 @@ class Iperf3(AutotoolsPackage):
     version("3.6", sha256="de5d51e46dc460cc590fb4d44f95e7cad54b74fea1eba7d6ebd6f8887d75946e")
 
     depends_on("c", type="build")  # generated
+
+    conflicts("%gcc@15:", when="@:3.18")  # https://github.com/esnet/iperf/issues/1838