diff --git a/build.go b/build.go
index dddc3b964..b3b7f5eee 100644
--- a/build.go
+++ b/build.go
@@ -380,6 +380,12 @@ func main() {
 		}
 	}
 
+	solarisMinVersion := GoVersion{Major: 1, Minor: 20, Patch: 0}
+	if env["GOARCH"] == "solaris" && !goVersion.AtLeast(solarisMinVersion) {
+		fmt.Fprintf(os.Stderr, "Detected version %s is too old, restic requires at least %s for Solaris\n", goVersion, solarisMinVersion)
+		os.Exit(1)
+	}
+
 	verbosePrintf("detected Go version %v\n", goVersion)
 
 	preserveSymbols := false
diff --git a/changelog/unreleased/pull-4201 b/changelog/unreleased/pull-4201
new file mode 100644
index 000000000..500bbdbb1
--- /dev/null
+++ b/changelog/unreleased/pull-4201
@@ -0,0 +1,9 @@
+Change: Require Go 1.20 for Solaris builds
+
+Building restic on Solaris now requires Go 1.20, as the library used to access
+Azure uses the mmap syscall, which is only available on Solaris starting from
+Go 1.20.
+
+All other platforms continue to build with Go 1.18.
+
+https://github.com/restic/restic/pull/4201
diff --git a/doc/020_installation.rst b/doc/020_installation.rst
index 4488e31f9..4d591356d 100644
--- a/doc/020_installation.rst
+++ b/doc/020_installation.rst
@@ -269,7 +269,8 @@ From Source
 ***********
 
 restic is written in the Go programming language and you need at least
-Go version 1.18. Building restic may also work with older versions of Go,
+Go version 1.18. Building for Solaris requires at least Go version 1.20.
+Building restic may also work with older versions of Go,
 but that's not supported. See the `Getting
 started <https://go.dev/doc/install>`__ guide of the Go project for
 instructions how to install Go.