diff --git a/CHANGES.md b/CHANGES.md
index 51e6ffe8..e1e50262 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -34,6 +34,9 @@ next
 - Restore promoted files when they are deleted or changed in the
   source tree (#760, fix #759, @diml)
 
+- Fix a crash when using an invalid alias name (#762, fixes #761,
+  @diml)
+
 1.0+beta20 (10/04/2018)
 -----------------------
 
diff --git a/src/jbuild.ml b/src/jbuild.ml
index 49ba8564..55202713 100644
--- a/src/jbuild.ml
+++ b/src/jbuild.ml
@@ -1159,9 +1159,16 @@ module Alias_conf = struct
     ; package : Package.t option
     }
 
+  let alias_name sexp =
+    let s = string sexp in
+    if Filename.basename s <> s then
+      of_sexp_errorf sexp "%S is not a valid alias name" s
+    else
+      s
+
   let v1 pkgs =
     record
-      (field "name" string                              >>= fun name ->
+      (field "name" alias_name                          >>= fun name ->
        field "deps" (list Dep_conf.t) ~default:[]       >>= fun deps ->
        field_o "package" (Scope_info.package pkgs)      >>= fun package ->
        field_o "action" (located Action.Unexpanded.t)   >>= fun action ->
diff --git a/test/blackbox-tests/test-cases/github761/run.t b/test/blackbox-tests/test-cases/github761/run.t
index 1f74f841..3091e162 100644
--- a/test/blackbox-tests/test-cases/github761/run.t
+++ b/test/blackbox-tests/test-cases/github761/run.t
@@ -1,23 +1,4 @@
   $ jbuilder build @bar
-  Internal error, please report upstream including the contents of _build/log.
-  Description: 
-  ("Alias0.make: Invalid alias" (name foo/bar) (dir _build/default))
-  Backtrace:
-  Raised at file "src/stdune/exn.ml", line 32, characters 5-10
-  Called from file "src/build_system.ml", line 228, characters 8-146
-  Called from file "src/gen_rules.ml", line 914, characters 16-49
-  Called from file "src/gen_rules.ml", line 964, characters 8-37
-  Called from file "src/stdune/list.ml", line 13, characters 10-13
-  Called from file "src/gen_rules.ml", line 955, characters 4-777
-  Called from file "src/gen_rules.ml", line 994, characters 19-30
-  Called from file "src/build_system.ml", line 889, characters 6-62
-  Called from file "src/build_system.ml", line 865, characters 6-59
-  Re-raised at file "src/build_system.ml", line 876, characters 6-17
-  Called from file "src/build_system.ml" (inlined), line 833, characters 32-63
-  Called from file "src/build_system.ml", line 843, characters 4-24
-  Called from file "src/build_interpret.ml", line 101, characters 24-40
-  Called from file "src/build_interpret.ml", line 60, characters 31-43
-  Called from file "src/build_interpret.ml", line 60, characters 31-43
-  Called from file "src/build_system.ml", line 1215, characters 10-108
-  Called from file "src/fiber/fiber.ml", line 359, characters 6-13
+  File "dune", line 2, characters 8-15:
+  Error: "foo/bar" is not a valid alias name
   [1]