diff --git a/flang/lib/Semantics/check-call.cpp b/flang/lib/Semantics/check-call.cpp
index 00636c052bfbf..1f2af55cbdd27 100644
--- a/flang/lib/Semantics/check-call.cpp
+++ b/flang/lib/Semantics/check-call.cpp
@@ -931,9 +931,10 @@ parser::Messages CheckExplicitInterface(const characteristics::Procedure &proc,
 bool CheckInterfaceForGeneric(const characteristics::Procedure &proc,
     evaluate::ActualArguments &actuals, const evaluate::FoldingContext &context,
     bool allowActualArgumentConversions) {
-  return !CheckExplicitInterface(
-      proc, actuals, context, nullptr, nullptr, allowActualArgumentConversions)
-              .AnyFatalError();
+  return proc.HasExplicitInterface() &&
+      !CheckExplicitInterface(proc, actuals, context, nullptr, nullptr,
+          allowActualArgumentConversions)
+           .AnyFatalError();
 }
 
 void CheckArguments(const characteristics::Procedure &proc,
diff --git a/flang/lib/Semantics/check-declarations.cpp b/flang/lib/Semantics/check-declarations.cpp
index 935c99401b3b8..1326baeb6a35b 100644
--- a/flang/lib/Semantics/check-declarations.cpp
+++ b/flang/lib/Semantics/check-declarations.cpp
@@ -1188,15 +1188,22 @@ void CheckHelper::CheckGeneric(
 void CheckHelper::CheckSpecificsAreDistinguishable(
     const Symbol &generic, const GenericDetails &details) {
   GenericKind kind{details.kind()};
-  const SymbolVector &specifics{details.specificProcs()};
-  std::size_t count{specifics.size()};
-  if (count < 2 || !kind.IsName()) {
+  if (!kind.IsName()) {
     return;
   }
   DistinguishabilityHelper helper{context_};
-  for (const Symbol &specific : specifics) {
+  for (const Symbol &specific : details.specificProcs()) {
     if (const Procedure * procedure{Characterize(specific)}) {
-      helper.Add(generic, kind, specific, *procedure);
+      if (procedure->HasExplicitInterface()) {
+        helper.Add(generic, kind, specific, *procedure);
+      } else {
+        if (auto *msg{messages_.Say(specific.name(),
+                "Specific procedure '%s' of generic interface '%s' must have an explicit interface"_err_en_US,
+                specific.name(), generic.name())}) {
+          msg->Attach(
+              generic.name(), "Definition of '%s'"_en_US, generic.name());
+        }
+      }
     }
   }
   helper.Check(generic.owner());
diff --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
index f4430d97a000a..3f56a257c75f5 100644
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -3138,24 +3138,25 @@ void InterfaceVisitor::ResolveSpecificsInGeneric(Symbol &generic) {
     const Symbol &specific{
         symbol == &symbol->GetUltimate() ? bypassed : *symbol};
     const Symbol &ultimate{bypassed.GetUltimate()};
-    if (!ultimate.has<SubprogramDetails>() &&
-        !ultimate.has<SubprogramNameDetails>()) {
-      Say(*name, "'%s' is not a subprogram"_err_en_US);
+    ProcedureDefinitionClass defClass{ClassifyProcedure(ultimate)};
+    if (defClass == ProcedureDefinitionClass::Module) {
+      // ok
+    } else if (kind == ProcedureKind::ModuleProcedure) {
+      Say(*name, "'%s' is not a module procedure"_err_en_US);
       continue;
-    }
-    if (kind == ProcedureKind::ModuleProcedure) {
-      if (const auto *nd{ultimate.detailsIf<SubprogramNameDetails>()}) {
-        if (nd->kind() != SubprogramKind::Module) {
-          Say(*name, "'%s' is not a module procedure"_err_en_US);
-        }
-      } else {
-        // USE-associated procedure
-        const auto *sd{ultimate.detailsIf<SubprogramDetails>()};
-        CHECK(sd);
-        if (ultimate.owner().kind() != Scope::Kind::Module ||
-            sd->isInterface()) {
-          Say(*name, "'%s' is not a module procedure"_err_en_US);
-        }
+    } else {
+      switch (defClass) {
+      case ProcedureDefinitionClass::Intrinsic:
+      case ProcedureDefinitionClass::External:
+      case ProcedureDefinitionClass::Internal:
+        break;
+      case ProcedureDefinitionClass::None:
+        Say(*name, "'%s' is not a procedure"_err_en_US);
+        continue;
+      default:
+        Say(*name,
+            "'%s' is not a procedure that can appear in a generic interface"_err_en_US);
+        continue;
       }
     }
     if (symbolsSeen.insert(ultimate).second /*true if added*/) {
diff --git a/flang/lib/Semantics/tools.cpp b/flang/lib/Semantics/tools.cpp
index 6f91024e3b528..f57548016f938 100644
--- a/flang/lib/Semantics/tools.cpp
+++ b/flang/lib/Semantics/tools.cpp
@@ -1149,6 +1149,14 @@ ProcedureDefinitionClass ClassifyProcedure(const Symbol &symbol) { // 15.2.2
     } else if (IsPointer(ultimate)) {
       return ProcedureDefinitionClass::Pointer;
     }
+  } else if (const auto *nameDetails{
+                 ultimate.detailsIf<SubprogramNameDetails>()}) {
+    switch (nameDetails->kind()) {
+    case SubprogramKind::Module:
+      return ProcedureDefinitionClass::Module;
+    case SubprogramKind::Internal:
+      return ProcedureDefinitionClass::Internal;
+    }
   } else if (const Symbol * subp{FindSubprogram(symbol)}) {
     if (const auto *subpDetails{subp->detailsIf<SubprogramDetails>()}) {
       if (subpDetails->stmtFunction()) {
diff --git a/flang/test/Semantics/generic02.f90 b/flang/test/Semantics/generic02.f90
new file mode 100644
index 0000000000000..e4f7fe671aae9
--- /dev/null
+++ b/flang/test/Semantics/generic02.f90
@@ -0,0 +1,12 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+program test
+  interface generic
+    subroutine explicit(n)
+      integer, intent(in) :: n
+    end subroutine
+    procedure implicit
+  end interface
+!ERROR: Specific procedure 'implicit' of generic interface 'generic' must have an explicit interface
+  external implicit
+  call generic(1)
+end
diff --git a/flang/test/Semantics/resolve15.f90 b/flang/test/Semantics/resolve15.f90
index 3a2f3d78b5693..29fcf6f7ee153 100644
--- a/flang/test/Semantics/resolve15.f90
+++ b/flang/test/Semantics/resolve15.f90
@@ -2,13 +2,13 @@
 module m
   real :: var
   interface i
-    !ERROR: 'var' is not a subprogram
+    !ERROR: 'var' is not a procedure
     procedure :: sub, var
     !ERROR: Procedure 'bad' not found
     procedure :: bad
   end interface
   interface operator(.foo.)
-    !ERROR: 'var' is not a subprogram
+    !ERROR: 'var' is not a procedure
     procedure :: var
     !ERROR: OPERATOR(.foo.) procedure 'sub' must be a function
     procedure :: sub
@@ -35,3 +35,13 @@ subroutine sub(x, y)
     logical, intent(in) :: y
   end
 end
+
+module m2
+  interface
+    module subroutine specific
+    end subroutine
+  end interface
+  interface generic
+     module procedure specific
+  end interface
+end module