src/cmd/go/internal/work/security.go      | 8 ++++----
 src/cmd/go/internal/work/security_test.go | 5 +++++

diff --git a/src/cmd/go/internal/work/security.go b/src/cmd/go/internal/work/security.go
index 3ee68ac1b4144e3ab32b9caa2094ddfd010cc558..0d9628241fd85e2bb0447eda1dae2b8c2a41d20e 100644
--- a/src/cmd/go/internal/work/security.go
+++ b/src/cmd/go/internal/work/security.go
@@ -42,8 +42,8 @@
 var re = lazyregexp.New
 
 var validCompilerFlags = []*lazyregexp.Regexp{
-	re(`-D([A-Za-z_].*)`),
-	re(`-U([A-Za-z_]*)`),
+	re(`-D([A-Za-z_][A-Za-z0-9_]*)(=[^@\-]*)?`),
+	re(`-U([A-Za-z_][A-Za-z0-9_]*)`),
 	re(`-F([^@\-].*)`),
 	re(`-I([^@\-].*)`),
 	re(`-O`),
@@ -51,8 +51,8 @@ 	re(`-O([^@\-].*)`),
 	re(`-W`),
 	re(`-W([^@,]+)`), // -Wall but not -Wa,-foo.
 	re(`-Wa,-mbig-obj`),
-	re(`-Wp,-D([A-Za-z_].*)`),
-	re(`-Wp,-U([A-Za-z_]*)`),
+	re(`-Wp,-D([A-Za-z_][A-Za-z0-9_]*)(=[^@,\-]*)?`),
+	re(`-Wp,-U([A-Za-z_][A-Za-z0-9_]*)`),
 	re(`-ansi`),
 	re(`-f(no-)?asynchronous-unwind-tables`),
 	re(`-f(no-)?blocks`),
diff --git a/src/cmd/go/internal/work/security_test.go b/src/cmd/go/internal/work/security_test.go
index 11e74f29c6a6a7f94c6eec7bb403537a726f762e..aec9789185e8a178a295e0b3f1146b1d94c21551 100644
--- a/src/cmd/go/internal/work/security_test.go
+++ b/src/cmd/go/internal/work/security_test.go
@@ -13,6 +13,7 @@ var goodCompilerFlags = [][]string{
 	{"-DFOO"},
 	{"-Dfoo=bar"},
 	{"-Ufoo"},
+	{"-Ufoo1"},
 	{"-F/Qt"},
 	{"-I/"},
 	{"-I/etc/passwd"},
@@ -24,6 +25,8 @@ 	{"-W"},
 	{"-Wall"},
 	{"-Wp,-Dfoo=bar"},
 	{"-Wp,-Ufoo"},
+	{"-Wp,-Dfoo1"},
+	{"-Wp,-Ufoo1"},
 	{"-fobjc-arc"},
 	{"-fno-objc-arc"},
 	{"-fomit-frame-pointer"},
@@ -78,6 +81,8 @@ 	{"-I-dir"},
 	{"-O@1"},
 	{"-Wa,-foo"},
 	{"-W@foo"},
+	{"-Wp,-DX,-D@X"},
+	{"-Wp,-UX,-U@X"},
 	{"-g@gdb"},
 	{"-g-gdb"},
 	{"-march=@dawn"},