diff --git a/Changelog.md b/Changelog.md
index d0d4d8dfa..cbecb3cd2 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -4,6 +4,7 @@ Features:
  * Support ``pragma experimental v0.5.0;`` to turn on upcoming breaking changes.
  * Code Generator: Added ``.selector`` member on external function types to retrieve their signature.
  * Optimizer: Add new optimization step to remove unused ``JUMPDEST``s.
+ * Syntax Checker: Warn if no visibility is specified on contract functions.
  * Type Checker: Display helpful warning for unused function arguments/return parameters.
  * Type Checker: Do not show the same error multiple times for events.
  * Type Checker: Greatly reduce the number of duplicate errors shown for duplicate constructors and functions.
diff --git a/libsolidity/analysis/SyntaxChecker.cpp b/libsolidity/analysis/SyntaxChecker.cpp
index d2571cd35..187eb26fa 100644
--- a/libsolidity/analysis/SyntaxChecker.cpp
+++ b/libsolidity/analysis/SyntaxChecker.cpp
@@ -138,7 +138,7 @@ bool SyntaxChecker::visit(WhileStatement const&)
 	return true;
 }
 
-void SyntaxChecker::endVisit(WhileStatement const&	)
+void SyntaxChecker::endVisit(WhileStatement const&)
 {
 	m_inLoopDepth--;
 }
@@ -193,6 +193,18 @@ bool SyntaxChecker::visit(PlaceholderStatement const&)
 	return true;
 }
 
+bool SyntaxChecker::visit(FunctionDefinition const& _function)
+{
+	if (_function.noVisibilitySpecified())
+		m_errorReporter.warning(
+			_function.location(),
+			"No visibility specified. Defaulting to \"" +
+			Declaration::visibilityToString(_function.visibility()) +
+			"\"."
+		);
+	return true;
+}
+
 bool SyntaxChecker::visit(FunctionTypeName const& _node)
 {
 	for (auto const& decl: _node.parameterTypeList()->parameters())
diff --git a/libsolidity/analysis/SyntaxChecker.h b/libsolidity/analysis/SyntaxChecker.h
index fa34bab31..7fffbec00 100644
--- a/libsolidity/analysis/SyntaxChecker.h
+++ b/libsolidity/analysis/SyntaxChecker.h
@@ -66,6 +66,7 @@ private:
 
 	virtual bool visit(PlaceholderStatement const& _placeholderStatement) override;
 
+	virtual bool visit(FunctionDefinition const& _function) override;
 	virtual bool visit(FunctionTypeName const& _node) override;
 
 	ErrorReporter& m_errorReporter;
diff --git a/libsolidity/ast/AST.h b/libsolidity/ast/AST.h
index cecc2f04e..75b8e9461 100644
--- a/libsolidity/ast/AST.h
+++ b/libsolidity/ast/AST.h
@@ -180,6 +180,7 @@ public:
 
 	/// @returns the declared name.
 	ASTString const& name() const { return *m_name; }
+	bool noVisibilitySpecified() const { return m_visibility == Visibility::Default; }
 	Visibility visibility() const { return m_visibility == Visibility::Default ? defaultVisibility() : m_visibility; }
 	bool isPublic() const { return visibility() >= Visibility::Public; }
 	virtual bool isVisibleInContract() const { return visibility() != Visibility::External; }