diff --git a/base/pkg/entry.jl b/base/pkg/entry.jl
index 15c8431b2a35c..23739a2936df0 100644
--- a/base/pkg/entry.jl
+++ b/base/pkg/entry.jl
@@ -574,10 +574,10 @@ function build(pkgs::Vector)
     isempty(errs) && return
     println(STDERR)
     warnbanner(label="[ BUILD ERRORS ]", """
-    WARNING: $(join(map(x->x[1],errs),", "," and ")) had build errors.
+    WARNING: $(join(keys(errs),", "," and ")) had build errors.
 
      - packages with build errors remain installed in $(pwd())
-     - build the package(s) and all dependencies with `Pkg.build("$(join(map(x->x[1],errs),"\", \""))")`
+     - build the package(s) and all dependencies with `Pkg.build("$(join(keys(errs),"\", \""))")`
      - build a single package by running its `deps/build.jl` script
     """)
 end
@@ -606,7 +606,7 @@ function updatehook(pkgs::Vector)
     isempty(errs) && return
     println(STDERR)
     warnbanner(label="[ UPDATE ERRORS ]", """
-    WARNING: $(join(map(x->x[1],errs),", "," and ")) had update errors.
+    WARNING: $(join(keys(errs),", "," and ")) had update errors.
 
      - Unrelated packages are unaffected
      - To retry, run Pkg.update() again
diff --git a/test/pkg.jl b/test/pkg.jl
index 4146717a45518..b228702396123 100644
--- a/test/pkg.jl
+++ b/test/pkg.jl
@@ -52,7 +52,7 @@ temp_pkg_dir() do
                 end
             end
             @test isa(ex,Pkg.PkgError)
-            @test ex.msg == "Cannot clone Example from notarealprotocol://github.com/JuliaLang/Example.jl.git. Unsupported URL protocol"
+            @test contains(ex.msg, "Cannot clone Example from notarealprotocol://github.com/JuliaLang/Example.jl.git")
         end
     end
 
@@ -257,4 +257,28 @@ temp_pkg_dir() do
 
     # Test Pkg.Read.url works
     @test Pkg.Read.url("Example") == "git://github.com/JuliaLang/Example.jl.git"
+
+    # issue #15789, build failure warning are printed correctly.
+    # Also makes sure `Pkg.build()` works even for non-git repo
+    begin
+        pth = joinpath(Pkg.dir(), "BuildFail")
+        mkdir(pth)
+        depspath = joinpath(pth, "deps")
+        mkdir(depspath)
+        depsbuild = joinpath(depspath, "build.jl")
+        touch(depsbuild)
+        # Pkg.build works without the src directory now
+        # but it's probably fine to require it.
+        msg = readstring(`$(Base.julia_cmd()) -f -e 'redirect_stderr(STDOUT); Pkg.build("BuildFail")'`)
+        @test contains(msg, "Building BuildFail")
+        @test !contains(msg, "ERROR")
+        open(depsbuild, "w") do fd
+            println(fd, "error(\"Throw build error\")")
+        end
+        msg = readstring(`$(Base.julia_cmd()) -f -e 'redirect_stderr(STDOUT); Pkg.build("BuildFail")'`)
+        @test contains(msg, "Building BuildFail")
+        @test contains(msg, "ERROR")
+        @test contains(msg, "Pkg.build(\"BuildFail\")")
+        @test contains(msg, "Throw build error")
+    end
 end