diff --git a/Cargo.lock b/Cargo.lock
index 685ab48a..c428a3ab 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -68,14 +68,13 @@ checksum = "d92bec98840b8f03a5ff5413de5293bfcd8bf96467cf5452609f939ec6f5de16"
 
 [[package]]
 name = "assert_cmd"
-version = "2.0.16"
+version = "2.0.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dc1835b7f27878de8525dc71410b5a31cdcc5f230aed5ba5df968e09c201b23d"
+checksum = "88903cb14723e4d4003335bb7f8a14f27691649105346a0f0957466c096adfe6"
 dependencies = [
  "anstyle",
  "bstr",
  "doc-comment",
- "libc",
  "predicates",
  "predicates-core",
  "predicates-tree",
@@ -244,9 +243,9 @@ dependencies = [
 
 [[package]]
 name = "ciborium"
-version = "0.2.2"
+version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "42e69ffd6f0917f5c029256a24d0161db17cea3997d185db0d35926308770f0e"
+checksum = "effd91f6c78e5a4ace8a5d3c0b6bfaec9e2baaef55f3efc00e45fb2e477ee926"
 dependencies = [
  "ciborium-io",
  "ciborium-ll",
@@ -261,9 +260,9 @@ checksum = "05afea1e0a06c9be33d539b876f1ce3692f4afea2cb41f740e7743225ed1c757"
 
 [[package]]
 name = "ciborium-ll"
-version = "0.2.2"
+version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "57663b653d948a338bfb3eeba9bb2fd5fcfaecb9e199e87e1eda4d9e8b240fd9"
+checksum = "defaa24ecc093c77630e6c15e17c51f5e187bf35ee514f4e2d67baaa96dae22b"
 dependencies = [
  "ciborium-io",
  "half",
@@ -467,10 +466,14 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "22ec99545bb0ed0ea7bb9b8e1e9122ea386ff8a48c0922e43f36d45ab09e0e80"
 
 [[package]]
-name = "crunchy"
-version = "0.2.2"
+name = "cstr"
+version = "0.2.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7a81dae078cea95a014a339291cec439d2f232ebe854a9d672b796c6afafa9b7"
+checksum = "68523903c8ae5aacfa32a0d9ae60cadeb764e1da14ee0d26b1f3089f13a54636"
+dependencies = [
+ "proc-macro2",
+ "quote",
+]
 
 [[package]]
 name = "cuda-config"
@@ -576,24 +579,24 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6184e33543162437515c2e2b48714794e37845ec9851711914eec9d308f6ebe8"
 
 [[package]]
-name = "dirs"
-version = "5.0.1"
+name = "dirs-next"
+version = "2.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "44c45a9d03d6676652bcb5e724c7e988de1acad23a711b5217ab9cbecbec2225"
+checksum = "b98cf8ebf19c3d1b223e151f99a4f9f0690dca41414773390fc824184ac833e1"
 dependencies = [
- "dirs-sys",
+ "cfg-if",
+ "dirs-sys-next",
 ]
 
 [[package]]
-name = "dirs-sys"
-version = "0.4.1"
+name = "dirs-sys-next"
+version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "520f05a5cbd335fae5a99ff7a6ab8627577660ee5cfd6a94a6a929b52ff0321c"
+checksum = "4ebda144c4fe02d1f7ea1a7d9641b6fc6b580adcfa024ae48797ecdeb6825b4d"
 dependencies = [
  "libc",
- "option-ext",
  "redox_users",
- "windows-sys 0.48.0",
+ "winapi",
 ]
 
 [[package]]
@@ -602,7 +605,7 @@ version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "330c60081dcc4c72131f8eb70510f1ac07223e5d4163db481a04a0befcffa412"
 dependencies = [
- "libloading 0.8.5",
+ "libloading",
 ]
 
 [[package]]
@@ -744,16 +747,16 @@ checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
 [[package]]
 name = "font-kit"
-version = "0.14.2"
+version = "0.13.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b64b34f4efd515f905952d91bc185039863705592c0c53ae6d979805dd154520"
+checksum = "2845a73bbd781e691ab7c2a028c579727cd254942e8ced57ff73e0eafd60de87"
 dependencies = [
  "bitflags 2.6.0",
  "byteorder",
  "core-foundation",
  "core-graphics",
  "core-text",
- "dirs",
+ "dirs-next",
  "dwrote",
  "float-ord",
  "freetype-sys",
@@ -923,13 +926,9 @@ checksum = "d2fabcfbdc87f4758337ca535fb41a6d701b65693ce38287d856d1674551ec9b"
 
 [[package]]
 name = "half"
-version = "2.4.1"
+version = "1.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6dd08c532ae367adf81c312a4580bc67f1d0fe8bc9c460520283f4c0ff277888"
-dependencies = [
- "cfg-if",
- "crunchy",
-]
+checksum = "1b43ede17f21864e81be2fa654110bf1e793774238d86ef8555c37e6519c0403"
 
 [[package]]
 name = "hashbrown"
@@ -989,7 +988,7 @@ checksum = "4842d5980dc311a7c8933c7b45534fdae84df5ae7939a0ae8e449a56d4beb3d2"
 dependencies = [
  "hdf5-src",
  "libc",
- "libloading 0.7.4",
+ "libloading",
  "pkg-config",
  "regex",
  "serde",
@@ -1315,16 +1314,6 @@ dependencies = [
  "winapi",
 ]
 
-[[package]]
-name = "libloading"
-version = "0.8.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4979f22fdb869068da03c9f7528f8297c6fd2606bc3a4affe42e6a823fdb8da4"
-dependencies = [
- "cfg-if",
- "windows-targets 0.52.6",
-]
-
 [[package]]
 name = "libm"
 version = "0.2.8"
@@ -1637,12 +1626,6 @@ version = "11.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b410bbe7e14ab526a0e86877eb47c6996a2bd7746f027ba551028c925390e4e9"
 
-[[package]]
-name = "option-ext"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "04744f49eae99ab78e0d5c0b603ab218f515ea8cfe5a456d7629ad883a3b6e7d"
-
 [[package]]
 name = "os_str_bytes"
 version = "6.6.1"
@@ -1754,9 +1737,9 @@ checksum = "953ec861398dccce10c670dfeaf3ec4911ca479e9c02154b3a215178c5f566f2"
 
 [[package]]
 name = "plotters"
-version = "0.3.7"
+version = "0.3.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5aeb6f403d7a4911efb1e33402027fc44f29b5bf6def3effcc22d7bb75f2b747"
+checksum = "a15b6eccb8484002195a3e44fe65a4ce8e93a625797a063735536fd59cb01cf3"
 dependencies = [
  "font-kit",
  "lazy_static",
@@ -1815,26 +1798,27 @@ dependencies = [
 
 [[package]]
 name = "predicates"
-version = "3.1.2"
+version = "3.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e9086cc7640c29a356d1a29fd134380bee9d8f79a17410aa76e7ad295f42c97"
+checksum = "09963355b9f467184c04017ced4a2ba2d75cbcb4e7462690d388233253d4b1a9"
 dependencies = [
  "anstyle",
  "difflib",
+ "itertools",
  "predicates-core",
 ]
 
 [[package]]
 name = "predicates-core"
-version = "1.0.8"
+version = "1.0.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ae8177bee8e75d6846599c6b9ff679ed51e882816914eec639944d7c9aa11931"
+checksum = "b794032607612e7abeb4db69adb4e33590fa6cf1149e95fd7cb00e634b92f174"
 
 [[package]]
 name = "predicates-tree"
-version = "1.0.11"
+version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "41b740d195ed3166cd147c8047ec98db0e22ec019eb8eeb76d343b795304fb13"
+checksum = "368ba315fb8c5052ab692e68a0eefec6ec57b23a36959c14496f0b0df2c0cecf"
 dependencies = [
  "predicates-core",
  "termtree",
@@ -2564,7 +2548,7 @@ version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
 dependencies = [
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -2771,10 +2755,11 @@ dependencies = [
 
 [[package]]
 name = "yeslogic-fontconfig-sys"
-version = "6.0.0"
+version = "5.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "503a066b4c037c440169d995b869046827dbc71263f6e8f3be6d77d4f3229dbd"
+checksum = "ffb6b23999a8b1a997bf47c7bb4d19ad4029c3327bb3386ebe0a5ff584b33c7a"
 dependencies = [
+ "cstr",
  "dlib",
  "once_cell",
  "pkg-config",
diff --git a/Cargo.toml b/Cargo.toml
index 2fb9434c..bf8c143a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -115,7 +115,7 @@ plotters = { version = "0.3.5", default-features = false, features = [
 
 [dev-dependencies]
 approx = "0.5.1"
-assert_cmd = "2.0.0"                                        # warning: 2.0.14 requires Rust 1.73.0
+assert_cmd = "<2.0.13"                                      # requires Rust 1.70.0
 criterion = { version = "0.4.0", default-features = false }
 indoc = "2.0.1"
 marlu = { version = "0.14.0", features = ["approx"] }
@@ -145,3 +145,12 @@ birli = { git = "https://github.com/MWATelescope/Birli", branch = "main" }
 # mwalib = { git = "https://github.com/MWATelescope/mwalib" }
 # mwa_hyperbeam = { path = "../mwa_hyperbeam" }
 mwa_hyperbeam = { git = "https://github.com/MWATelescope/mwa_hyperbeam", branch = "marlu0.14" }
+
+# commands to maintain msrv 1.64 after cargo update:
+# cargo update -p plotters --precise 0.3.6
+# cargo update -p predicates --precise 3.0.3
+# cargo update -p ciborium --precise 0.2.1
+# cargo update -p ciborium-ll --precise 0.2.1
+# cargo update -p assert_cmd --precise 2.0.12
+# cargo update -p predicates-core --precise 1.0.6
+# cargo update -p predicates-tree --precise 1.0.9
diff --git a/build.rs b/build.rs
index 43050317..0ab045a3 100644
--- a/build.rs
+++ b/build.rs
@@ -118,7 +118,7 @@ mod gpu {
                     }
 
                     cuda_target.flag("-gencode");
-                    cuda_target.flag(&format!("arch=compute_{arch},code=sm_{sm}"));
+                    cuda_target.flag(format!("arch=compute_{arch},code=sm_{sm}"));
                 }
             }