diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index 59955b273342..e8e54c3cfaac 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -287,8 +287,9 @@ impl CheckAttrVisitor<'tcx> {
                             self.doc_alias_str_error(meta);
                             return false;
                         }
-                        if let Some(c) =
-                            doc_alias.chars().find(|&c| c == '"' || c == '\'' || c.is_whitespace())
+                        if let Some(c) = doc_alias
+                            .chars()
+                            .find(|&c| c == '"' || c == '\'' || (c.is_whitespace() && c != ' '))
                         {
                             self.tcx
                                 .sess
diff --git a/src/test/rustdoc-ui/check-doc-alias-attr.rs b/src/test/rustdoc-ui/check-doc-alias-attr.rs
index c8bec39fad61..d55be9f120ca 100644
--- a/src/test/rustdoc-ui/check-doc-alias-attr.rs
+++ b/src/test/rustdoc-ui/check-doc-alias-attr.rs
@@ -11,6 +11,5 @@ pub struct Bar;
 #[doc(alias = "\n")] //~ ERROR
 #[doc(alias = "
 ")] //~^ ERROR
-#[doc(alias = " ")] //~ ERROR
 #[doc(alias = "\t")] //~ ERROR
 pub struct Foo;
diff --git a/src/test/rustdoc-ui/check-doc-alias-attr.stderr b/src/test/rustdoc-ui/check-doc-alias-attr.stderr
index be7d7b3dbea9..97444c69ff1d 100644
--- a/src/test/rustdoc-ui/check-doc-alias-attr.stderr
+++ b/src/test/rustdoc-ui/check-doc-alias-attr.stderr
@@ -36,17 +36,11 @@ LL |   #[doc(alias = "
 LL | | ")]
    | |_^
 
-error: ' ' character isn't allowed in `#[doc(alias = "...")]`
-  --> $DIR/check-doc-alias-attr.rs:14:7
-   |
-LL | #[doc(alias = " ")]
-   |       ^^^^^^^^^^^
-
 error: '\t' character isn't allowed in `#[doc(alias = "...")]`
-  --> $DIR/check-doc-alias-attr.rs:15:7
+  --> $DIR/check-doc-alias-attr.rs:14:7
    |
 LL | #[doc(alias = "\t")]
    |       ^^^^^^^^^^^^
 
-error: aborting due to 8 previous errors
+error: aborting due to 7 previous errors
 
diff --git a/src/test/ui/check-doc-alias-attr.rs b/src/test/ui/check-doc-alias-attr.rs
index c8bec39fad61..d55be9f120ca 100644
--- a/src/test/ui/check-doc-alias-attr.rs
+++ b/src/test/ui/check-doc-alias-attr.rs
@@ -11,6 +11,5 @@ pub struct Bar;
 #[doc(alias = "\n")] //~ ERROR
 #[doc(alias = "
 ")] //~^ ERROR
-#[doc(alias = " ")] //~ ERROR
 #[doc(alias = "\t")] //~ ERROR
 pub struct Foo;
diff --git a/src/test/ui/check-doc-alias-attr.stderr b/src/test/ui/check-doc-alias-attr.stderr
index be7d7b3dbea9..97444c69ff1d 100644
--- a/src/test/ui/check-doc-alias-attr.stderr
+++ b/src/test/ui/check-doc-alias-attr.stderr
@@ -36,17 +36,11 @@ LL |   #[doc(alias = "
 LL | | ")]
    | |_^
 
-error: ' ' character isn't allowed in `#[doc(alias = "...")]`
-  --> $DIR/check-doc-alias-attr.rs:14:7
-   |
-LL | #[doc(alias = " ")]
-   |       ^^^^^^^^^^^
-
 error: '\t' character isn't allowed in `#[doc(alias = "...")]`
-  --> $DIR/check-doc-alias-attr.rs:15:7
+  --> $DIR/check-doc-alias-attr.rs:14:7
    |
 LL | #[doc(alias = "\t")]
    |       ^^^^^^^^^^^^
 
-error: aborting due to 8 previous errors
+error: aborting due to 7 previous errors