diff --git a/master_changes.md b/master_changes.md
index 5247c0c2808..5669f8e450d 100644
--- a/master_changes.md
+++ b/master_changes.md
@@ -60,6 +60,7 @@ users)
 ## Exec
 
 ## Source
+  * [NEW] Add options `--require-checksums` and `--no-checksums` to harmonise with `opam install` [#5563 @rjbou]
 
 ## Lint
 
@@ -172,6 +173,7 @@ users)
 # API updates
 ## opam-client
   * `OpamArg.InvalidCLI`: export exception [#6150 @rjbou]
+  * `OpamArg`: export `require_checksums` and `no_checksums`, that are shared with `build_options` [#5563 @rjbou]
 
 ## opam-repository
   * `OpamDownload.get_output`: fix `wget` option for `POST` requests [#6036 @rjbou]
diff --git a/src/client/opamArg.ml b/src/client/opamArg.ml
index 4c978609738..14c25057846 100644
--- a/src/client/opamArg.ml
+++ b/src/client/opamArg.ml
@@ -1412,6 +1412,17 @@ let lock_suffix ?section cli =
     "Set locked files suffix to $(i,SUFFIX)."
     Arg.(string) ("locked")
 
+(* Checksums options *)
+let no_checksums ?section cli from_cli =
+  mk_flag ~cli from_cli ?section ["no-checksums"]
+    "Do not verify the checksum of downloaded archives.\
+     This is equivalent to setting $(b,\\$OPAMNOCHECKSUMS) to \"true\"."
+let require_checksums ?section cli from_cli =
+  mk_flag ~cli from_cli ?section ["require-checksums"]
+    "Reject the installation of packages that don't provide a checksum for\
+     the upstream archives.  This is equivalent to setting \
+     $(b,\\$OPAMREQUIRECHECKSUMS) to \"true\"."
+
 (* Options common to all build commands *)
 let build_option_section = "PACKAGE BUILD OPTIONS"
 let man_build_option_section =
@@ -1440,14 +1451,8 @@ let build_options cli =
        affects packages that are explicitly listed on the command-line. \
        This is equivalent to setting $(b,\\$OPAMINPLACEBUILD) to \"true\"."
   in
-  let no_checksums =
-    mk_flag ~cli cli_original ~section ["no-checksums"]
-      "Do not verify the checksum of downloaded archives.\
-       This is equivalent to setting $(b,\\$OPAMNOCHECKSUMS) to \"true\"." in
-  let req_checksums =
-    mk_flag ~cli cli_original ~section ["require-checksums"]
-      "Reject the installation of packages that don't provide a checksum for the upstream archives. \
-       This is equivalent to setting $(b,\\$OPAMREQUIRECHECKSUMS) to \"true\"." in
+  let no_checksums = no_checksums ~section cli cli_original in
+  let req_checksums = require_checksums ~section cli cli_original in
   let build_test =
     mk_flag_replaced ~cli ~section [
       cli_between cli2_0 cli2_1 ~replaced:"--with-test", ["build-test"];
diff --git a/src/client/opamArg.mli b/src/client/opamArg.mli
index 75a31250362..03dfea6a62b 100644
--- a/src/client/opamArg.mli
+++ b/src/client/opamArg.mli
@@ -213,6 +213,12 @@ val apply_build_options: OpamCLIVersion.Sourced.t -> build_options -> unit
 val locked: ?section:string -> OpamCLIVersion.Sourced.t -> bool Term.t
 val lock_suffix: ?section:string -> OpamCLIVersion.Sourced.t -> string Term.t
 
+(** Checksum options *)
+val no_checksums:
+  ?section:string -> OpamCLIVersion.Sourced.t -> validity -> bool Term.t
+val require_checksums:
+  ?section:string -> OpamCLIVersion.Sourced.t -> validity -> bool Term.t
+
 (** {3 Package listing and filtering options} *)
 
 (** Man section name *)
diff --git a/src/client/opamCommands.ml b/src/client/opamCommands.ml
index 9e2827ff733..78d4d5b9641 100644
--- a/src/client/opamCommands.ml
+++ b/src/client/opamCommands.ml
@@ -3703,8 +3703,19 @@ let source cli =
       "Choose package without consideration for \
        the current (or any other) switch (installed or pinned packages, etc.)"
   in
-  let source global_options atom dev_repo pin no_switch dir () =
+  let no_checksums = no_checksums cli (cli_from cli2_4) in
+  let req_checksums = require_checksums cli (cli_from cli2_4) in
+  let source global_options atom dev_repo pin no_switch dir
+      no_checksums req_checksums () =
     apply_global_options cli global_options;
+    let force_checksums =
+      if req_checksums then Some (Some true)
+      else if no_checksums then Some (Some false)
+      else None
+    in
+    OpamStd.Option.iter (fun force_checksums ->
+        OpamRepositoryConfig.update ~force_checksums ())
+      force_checksums;
     OpamGlobalState.with_ `Lock_none @@ fun gt ->
     let get_package_dir t =
       let nv =
@@ -3829,9 +3840,11 @@ let source cli =
       OpamSwitchState.drop
         (OpamClient.PIN.pin t nv.name ~version:nv.version target)
   in
-  mk_command  ~cli cli_original "source" ~doc ~man
+  mk_command ~cli cli_original "source" ~doc ~man
     Term.(const source
-          $global_options cli $atom $dev_repo $pin $no_switch $dir)
+          $global_options cli
+          $atom $dev_repo $pin $no_switch $dir
+          $no_checksums $req_checksums)
 
 (* LINT *)
 let lint_doc = "Checks and validate package description ('opam') files."
diff --git a/tests/reftests/archive.test b/tests/reftests/archive.test
index cea652b2ac6..ff5965783ab 100644
--- a/tests/reftests/archive.test
+++ b/tests/reftests/archive.test
@@ -285,6 +285,10 @@ Done.
 ### opam source good-md5
 Successfully extracted to ${BASEDIR}/good-md5.1
 ### test -f good-md5.1/hello
+### rm -r good-md5.1
+### opam source good-md5 --require-checksums
+Successfully extracted to ${BASEDIR}/good-md5.1
+### test -f good-md5.1/hello
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:2: good sha256
@@ -321,6 +325,10 @@ Done.
 ### opam source good-sha256
 Successfully extracted to ${BASEDIR}/good-sha256.1
 ### test -f good-sha256.1/hello
+### rm -r good-sha256.1
+### opam source good-sha256 --require-checksums
+Successfully extracted to ${BASEDIR}/good-sha256.1
+### test -f good-sha256.1/hello
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:3: good md5 & sha256
@@ -375,6 +383,10 @@ Done.
 ### opam source good-md5-good-sha256
 Successfully extracted to ${BASEDIR}/good-md5-good-sha256.1
 ### test -f good-md5-good-sha256.1/hello
+### rm -r good-md5-good-sha256.1
+### opam source good-md5-good-sha256 --require-checksums
+Successfully extracted to ${BASEDIR}/good-md5-good-sha256.1
+### test -f good-md5-good-sha256.1/hello
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:4: good sha256 & good md5
@@ -426,6 +438,10 @@ Done.
 ### opam source good-sha256-good-md5
 Successfully extracted to ${BASEDIR}/good-sha256-good-md5.1
 ### test -f good-sha256-good-md5.1/hello
+### rm -r good-sha256-good-md5.1
+### opam source good-sha256-good-md5 --require-checksums
+Successfully extracted to ${BASEDIR}/good-sha256-good-md5.1
+### test -f good-sha256-good-md5.1/hello
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:5: no checksum
@@ -472,6 +488,12 @@ OpamSolution.Fetch_fail("no-checksum.1: Missing checksum, and `--require-checksu
 ### opam source no-checksum
 Successfully extracted to ${BASEDIR}/no-checksum.1
 ### test -f no-checksum.1/hello
+### rm -r no-checksum.1
+### opam source no-checksum --require-checksums
+[ERROR] Download failed: no-checksum.1: Missing checksum, and `--require-checksums` was set.
+# Return code 40 #
+### test -f no-checksum.1/hello
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:6: multiple md5
@@ -534,6 +556,14 @@ OpamSolution.Fetch_fail("Checksum mismatch")
 # Return code 40 #
 ### test -f multiple-md5.1/hello
 # Return code 1 #
+### opam source multiple-md5 --require-checksums | '[0-9a-z]{32}' -> 'hash'
+[ERROR] multiple-md5.1: Checksum mismatch for file://${BASEDIR}/archive.tgz:
+          expected md5=hash
+          got      md5=hash
+[ERROR] Download failed: Checksum mismatch
+# Return code 40 #
+### test -f multiple-md5.1/hello
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:7: bad md5
@@ -593,6 +623,14 @@ OpamSolution.Fetch_fail("Checksum mismatch")
 # Return code 40 #
 ### test -f bad-md5.1/hello
 # Return code 1 #
+### opam source bad-md5 --require-checksums | '[0-9a-z]{32}' -> 'hash'
+[ERROR] bad-md5.1: Checksum mismatch for file://${BASEDIR}/archive.tgz:
+          expected md5=hash
+          got      md5=hash
+[ERROR] Download failed: Checksum mismatch
+# Return code 40 #
+### test -f bad-md5.1/hello
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:8: good md5 & bad sha256
@@ -722,6 +760,14 @@ OpamSolution.Fetch_fail("Checksum mismatch")
 # Return code 40 #
 ### test -f good-md5-bad-sha256.1/hello
 # Return code 1 #
+### opam source good-md5-bad-sha256 --require-checksums | '[0-9a-z]{64}' -> 'md5'
+[ERROR] good-md5-bad-sha256.1: Checksum mismatch for file://${BASEDIR}/archive.tgz:
+          expected sha256=md5
+          got      sha256=md5
+[ERROR] Download failed: Checksum mismatch
+# Return code 40 #
+### test -f good-md5-bad-sha256.1/hello
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:9: good sha256 & bad md5
@@ -781,6 +827,14 @@ OpamSolution.Fetch_fail("Checksum mismatch")
 # Return code 40 #
 ### test -f good-sha256-bad-md5.1/hello
 # Return code 1 #
+### opam source good-sha256-bad-md5 --require-checksums | '[0-9a-z]{32}' -> 'hash'
+[ERROR] good-sha256-bad-md5.1: Checksum mismatch for file://${BASEDIR}/archive.tgz:
+          expected md5=hash
+          got      md5=hash
+[ERROR] Download failed: Checksum mismatch
+# Return code 40 #
+### test -f good-sha256-bad-md5.1/hello
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:10: clash with all md5
@@ -928,6 +982,14 @@ OpamSolution.Fetch_fail("Checksum mismatch")
 # Return code 40 #
 ### test -f clash-with-all-md5s.666/hello
 # Return code 1 #
+### opam source clash-with-all-md5s --require-checksums | '[0-9a-z]{32}' -> 'hash'
+[ERROR] clash-with-all-md5s.666: Checksum mismatch for file://${BASEDIR}/archive.tgz:
+          expected md5=hash
+          got      md5=hash
+[ERROR] Download failed: Checksum mismatch
+# Return code 40 #
+### test -f clash-with-all-md5s.666/hello
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :::::::::::::::::
diff --git a/tests/reftests/extrafile.test b/tests/reftests/extrafile.test
index ff822f46d4a..d5a746ebbfa 100644
--- a/tests/reftests/extrafile.test
+++ b/tests/reftests/extrafile.test
@@ -196,6 +196,10 @@ Done.
 ### opam source good-md5
 Successfully extracted to ${BASEDIR}/good-md5.1
 ### test -f good-md5.1/p.patch
+### rm -r good-md5.1
+### opam source good-md5 --require-checksums
+Successfully extracted to ${BASEDIR}/good-md5.1
+### test -f good-md5.1/p.patch
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:2: good md5 & sha256
@@ -234,6 +238,10 @@ Done.
 ### opam source good-md5-good-sha256
 Successfully extracted to ${BASEDIR}/good-md5-good-sha256.1
 ### test -f good-md5-good-sha256.1/p.patch
+### rm -r good-md5-good-sha256.1
+### opam source good-md5-good-sha256 --require-checksums
+Successfully extracted to ${BASEDIR}/good-md5-good-sha256.1
+### test -f good-md5-good-sha256.1/p.patch
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:3: bad md5
@@ -282,6 +290,12 @@ Bad hash for   - ${BASEDIR}/OPAM/repo/default/packages/bad-md5/bad-md5.1/files/p
 ### opam source bad-md5 | '.n"' -> '"'
 [WARNING] Some errors extracting to ${BASEDIR}/bad-md5.1: Failure("Bad hash for   - ${BASEDIR}/OPAM/repo/default/packages/bad-md5/bad-md5.1/files/p.patch")
 
+### test -f bad-md5.1/p.patch
+# Return code 1 #
+### rm -r bad-md5.1
+### opam source bad-md5 --require-checksums | '.n"' -> '"'
+[WARNING] Some errors extracting to ${BASEDIR}/bad-md5.1: Failure("Bad hash for   - ${BASEDIR}/OPAM/repo/default/packages/bad-md5/bad-md5.1/files/p.patch")
+
 ### test -f bad-md5.1/p.patch
 # Return code 1 #
 ### opam clean --download-cache
@@ -332,6 +346,11 @@ Bad hash for   - ${BASEDIR}/OPAM/repo/default/packages/good-md5-bad-sha256/good-
 ### opam source good-md5-bad-sha256 | '.n"' -> '"'
 [WARNING] Some errors extracting to ${BASEDIR}/good-md5-bad-sha256.1: Failure("Bad hash for   - ${BASEDIR}/OPAM/repo/default/packages/good-md5-bad-sha256/good-md5-bad-sha256.1/files/p.patch")
 
+### test -f good-md5-bad-sha256.1/p.patch
+### rm -r good-md5-bad-sha256.1
+### opam source good-md5-bad-sha256 --require-checksums | '.n"' -> '"'
+[WARNING] Some errors extracting to ${BASEDIR}/good-md5-bad-sha256.1: Failure("Bad hash for   - ${BASEDIR}/OPAM/repo/default/packages/good-md5-bad-sha256/good-md5-bad-sha256.1/files/p.patch")
+
 ### test -f good-md5-bad-sha256.1/p.patch
 ### opam clean --download-cache
 Clearing cache of downloaded files
@@ -395,6 +414,11 @@ The following actions will be performed:
 Successfully extracted to ${BASEDIR}/no-checksum.1
 ### test -f no-checksum.1/p.patch
 # Return code 1 #
+### rm -r no-checksum.1
+### opam source no-checksum --require-checksums
+Successfully extracted to ${BASEDIR}/no-checksum.1
+### test -f no-checksum.1/p.patch
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :::::::::::::::::
@@ -447,6 +471,11 @@ The following actions will be performed:
 Successfully extracted to ${BASEDIR}/not-mentioned.1
 ### test -f not-mentioned.1/p.patch
 # Return code 1 #
+### rm -r not-mentioned.1
+### opam source not-mentioned --require-checksums
+Successfully extracted to ${BASEDIR}/not-mentioned.1
+### test -f not-mentioned.1/p.patch
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :II:2: not present
diff --git a/tests/reftests/extrasource.test b/tests/reftests/extrasource.test
index c5445355894..f64af3722d5 100644
--- a/tests/reftests/extrasource.test
+++ b/tests/reftests/extrasource.test
@@ -398,6 +398,10 @@ Done.
 ### opam source good-sha256
 Successfully extracted to ${BASEDIR}/good-sha256.1
 ### test -f good-sha256.1/i-am-a-patch
+### rm -r good-sha256.1
+### opam source good-sha256 --require-checksums
+Successfully extracted to ${BASEDIR}/good-sha256.1
+### test -f good-sha256.1/i-am-a-patch
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:3: good md5 & sha256
@@ -450,6 +454,10 @@ Done.
 ### opam source good-md5-good-sha256
 Successfully extracted to ${BASEDIR}/good-md5-good-sha256.1
 ### test -f good-md5-good-sha256.1/i-am-a-patch
+### rm -r good-md5-good-sha256.1
+### opam source good-md5-good-sha256 --require-checksums
+Successfully extracted to ${BASEDIR}/good-md5-good-sha256.1
+### test -f good-md5-good-sha256.1/i-am-a-patch
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:4: good sha256 & good md5
@@ -501,6 +509,10 @@ Done.
 ### opam source good-sha256-good-md5
 Successfully extracted to ${BASEDIR}/good-sha256-good-md5.1
 ### test -f good-sha256-good-md5.1/i-am-a-patch
+### rm -r good-sha256-good-md5.1
+### opam source good-sha256-good-md5 --require-checksums
+Successfully extracted to ${BASEDIR}/good-sha256-good-md5.1
+### test -f good-sha256-good-md5.1/i-am-a-patch
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:5: no checksum
@@ -545,6 +557,12 @@ no-checksum.1/i-am-a-patch: Missing checksum, and `--require-checksums` was set.
 ### opam source no-checksum
 Successfully extracted to ${BASEDIR}/no-checksum.1
 ### test -f no-checksum.1/i-am-a-patch
+### rm -r no-checksum.1
+### opam source no-checksum --require-checksums
+[WARNING] Some errors extracting to ${BASEDIR}/no-checksum.1: Failure("no-checksum.1/i-am-a-patch: Missing checksum, and `--require-checksums` was set.")
+
+### test -f no-checksum.1/i-am-a-patch
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:6: multiple md5
@@ -604,6 +622,14 @@ OpamSolution.Fetch_fail("Checksum mismatch")
 # Return code 40 #
 ### test -f multiple-md5.1/i-am-a-patch
 # Return code 1 #
+### opam source multiple-md5 --require-checksums | '[0-9a-z]{32}' -> 'hash'
+[ERROR] multiple-md5.1/i-am-a-patch: Checksum mismatch for file://${BASEDIR}/p.patch:
+          expected md5=hash
+          got      md5=hash
+[ERROR] Download failed: Checksum mismatch
+# Return code 40 #
+### test -f multiple-md5.1/i-am-a-patch
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:7: bad md5
@@ -659,6 +685,14 @@ OpamSolution.Fetch_fail("Checksum mismatch")
 # Return code 40 #
 ### test -f bad-md5.1/i-am-a-patch
 # Return code 1 #
+### opam source bad-md5 --require-checksums | '[0-9a-z]{32}' -> 'hash'
+[ERROR] bad-md5.1/i-am-a-patch: Checksum mismatch for file://${BASEDIR}/p.patch:
+          expected md5=hash
+          got      md5=hash
+[ERROR] Download failed: Checksum mismatch
+# Return code 40 #
+### test -f bad-md5.1/i-am-a-patch
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:8: good md5 & bad sha256
@@ -784,6 +818,14 @@ OpamSolution.Fetch_fail("Checksum mismatch")
 # Return code 40 #
 ### test -f good-md5-bad-sha256.1/i-am-a-patch
 # Return code 1 #
+### opam source good-md5-bad-sha256 --require-checksums | '[0-9a-z]{64}' -> 'md5'
+[ERROR] good-md5-bad-sha256.1/i-am-a-patch: Checksum mismatch for file://${BASEDIR}/p.patch:
+          expected sha256=md5
+          got      sha256=md5
+[ERROR] Download failed: Checksum mismatch
+# Return code 40 #
+### test -f good-md5-bad-sha256.1/i-am-a-patch
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:9: good sha256 & bad md5
@@ -839,6 +881,14 @@ OpamSolution.Fetch_fail("Checksum mismatch")
 # Return code 40 #
 ### test -f good-sha256-bad-md5.1/i-am-a-patch
 # Return code 1 #
+### opam source good-sha256-bad-md5 --require-checksums | '[0-9a-z]{32}' -> 'hash'
+[ERROR] good-sha256-bad-md5.1/i-am-a-patch: Checksum mismatch for file://${BASEDIR}/p.patch:
+          expected md5=hash
+          got      md5=hash
+[ERROR] Download failed: Checksum mismatch
+# Return code 40 #
+### test -f good-sha256-bad-md5.1/i-am-a-patch
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :I:10: clash with all md5
@@ -967,6 +1017,14 @@ OpamSolution.Fetch_fail("Checksum mismatch")
 # Return code 40 #
 ### test -f clash-with-all-md5s.666/i-am-a-patch
 # Return code 1 #
+### opam source clash-with-all-md5s --require-checksums | '[0-9a-z]{32}' -> 'hash'
+[ERROR] clash-with-all-md5s.666/i-am-a-patch: Checksum mismatch for file://${BASEDIR}/p.patch:
+          expected md5=hash
+          got      md5=hash
+[ERROR] Download failed: Checksum mismatch
+# Return code 40 #
+### test -f clash-with-all-md5s.666/i-am-a-patch
+# Return code 1 #
 ### opam clean --download-cache
 Clearing cache of downloaded files
 ### :::::::::::::::::
@@ -1019,6 +1077,11 @@ The following actions will be performed:
 Successfully extracted to ${BASEDIR}/not-mentioned.1
 ### test -f not-mentioned.1/i-am-a-patch
 # Return code 1 #
+### rm -r not-mentioned.1
+### opam source not-mentioned --require-checksums
+Successfully extracted to ${BASEDIR}/not-mentioned.1
+### test -f not-mentioned.1/i-am-a-patch
+# Return code 1 #
 ### :II:2: Double extra-source
 ### opam lint --package multiple
 <default>/multiple.1: Errors.
@@ -1069,6 +1132,10 @@ Done.
 ### opam source multiple
 Successfully extracted to ${BASEDIR}/multiple.1
 ### test -f multiple.1/i-am-a-patch
+### rm -r multiple.1
+### opam source multiple --require-checksums
+Successfully extracted to ${BASEDIR}/multiple.1
+### test -f multiple.1/i-am-a-patch
 ### :::::::::::::::::
 ### :III: Cache manipulation
 ### :::::::::::::::::
@@ -1250,6 +1317,10 @@ Done.
 ### opam source escape-absolute
 Successfully extracted to ${BASEDIR}/escape-absolute.1
 ### test -f escape-absolute.1/etc/passwd
+### rm -r escape-absolute.1
+### opam source escape-absolute --require-checksums
+Successfully extracted to ${BASEDIR}/escape-absolute.1
+### test -f escape-absolute.1/etc/passwd
 ### :IV:2: good md5
 ### # /!\ all escape!!!
 ### opam lint --package escape-build-good-md5
@@ -1289,3 +1360,7 @@ Done.
 ### opam source escape-source-good-md5
 Successfully extracted to ${BASEDIR}/escape-source-good-md5.1
 ### test -f shouldnt-exist
+### rm -r escape-source-good-md5.1
+### opam source escape-source-good-md5 --require-checksums
+Successfully extracted to ${BASEDIR}/escape-source-good-md5.1
+### test -f shouldnt-exist