diff --git a/packages/mirage-unikernel-smtp-relay-hvt.0.0.1/opam b/packages/mirage-unikernel-smtp-relay-hvt.0.0.1/opam
index d4be29d..acfe0ba 100644
--- a/packages/mirage-unikernel-smtp-relay-hvt.0.0.1/opam
+++ b/packages/mirage-unikernel-smtp-relay-hvt.0.0.1/opam
@@ -47,7 +47,7 @@ depends: [
   "opam-monorepo" { build & >= "0.3.2" }
   "ptt" { ?monorepo }
   "randomconv" { ?monorepo }
-  "solo5" { build & >= "0.7.5" & < "0.9.0" }
+  "solo5" { build & >= "0.7.5" & < "0.8.0" }
   "tcpip" { ?monorepo & >= "7.0.0" & >= "7.1.0" & < "9.0.0" }
 ]
 
diff --git a/packages/mirage-unikernel-smtp-signer-hvt.0.0.1/opam b/packages/mirage-unikernel-smtp-signer-hvt.0.0.1/opam
index 9dfe7a3..f253430 100644
--- a/packages/mirage-unikernel-smtp-signer-hvt.0.0.1/opam
+++ b/packages/mirage-unikernel-smtp-signer-hvt.0.0.1/opam
@@ -46,7 +46,7 @@ depends: [
   "opam-monorepo" { build & >= "0.3.2" }
   "ptt" { ?monorepo }
   "randomconv" { ?monorepo }
-  "solo5" { build & >= "0.7.5" & < "0.9.0" }
+  "solo5" { build & >= "0.7.5" & < "0.8.0" }
   "tcpip" { ?monorepo & >= "7.0.0" & < "9.0.0" }
 ]
 
diff --git a/packages/mirage-unikernel-smtp-submission-hvt.0.0.1/opam b/packages/mirage-unikernel-smtp-submission-hvt.0.0.1/opam
index e393afd..9a3f429 100644
--- a/packages/mirage-unikernel-smtp-submission-hvt.0.0.1/opam
+++ b/packages/mirage-unikernel-smtp-submission-hvt.0.0.1/opam
@@ -50,7 +50,7 @@ depends: [
   "opam-monorepo" { build & >= "0.3.2" }
   "ptt" { ?monorepo }
   "randomconv" { ?monorepo }
-  "solo5" { build & >= "0.7.5" & < "0.9.0" }
+  "solo5" { build & >= "0.7.5" & < "0.8.0" }
   "tcpip" { ?monorepo & >= "7.0.0" & >= "7.1.0" & < "9.0.0" }
 ]