diff --git a/opast.cc b/opast.cc
index 8d98a47..1e07155 100644
--- a/opast.cc
+++ b/opast.cc
@@ -129,14 +129,14 @@ T_Optional< T_SRDLocation > T_FuncNode::addArgument(
 T_PipelineInstrNode::T_PipelineInstrNode(
 		T_InstrListNode& parent ,
 		T_SRDToken const& idToken ) noexcept
-	: A_InstructionNode( OP_PIPELINE , parent ) ,
+	: A_InstructionNode( OP_PIPELINE , parent , E_InstrRestriction::FRAME ) ,
 		id_( idToken.stringValue( ) ) ,
 		idLocation_( idToken.location( ) )
 { }
 
 T_PipelineInstrNode::T_PipelineInstrNode(
 		T_InstrListNode& parent ) noexcept
-	: A_InstructionNode( OP_PIPELINE , parent ) ,
+	: A_InstructionNode( OP_PIPELINE , parent , E_InstrRestriction::FRAME ) ,
 		id_( "*invalid*" ) ,
 		idLocation_{ }
 { }
@@ -160,7 +160,7 @@ T_Optional< T_SRDLocation > T_PipelineInstrNode::addProgram(
 T_ProfileInstrNode::T_ProfileInstrNode(
 		T_InstrListNode& parent ,
 		T_String const& text ) noexcept
-	: A_InstructionNode( OP_PROFILE , parent ) ,
+	: A_InstructionNode( OP_PROFILE , parent , E_InstrRestriction::INIT ) ,
 		text_( text ) ,
 		instructions_( *this )
 { }
@@ -172,7 +172,7 @@ T_ProgramInstrNode::T_ProgramInstrNode(
 		T_InstrListNode& parent ,
 		T_SRDToken const& idToken ,
 		T_SRDToken const& pathToken ) noexcept
-	: A_InstructionNode( OP_PROGRAM , parent ) ,
+	: A_InstructionNode( OP_PROGRAM , parent , E_InstrRestriction::FRAME ) ,
 		id_( idToken.stringValue( ) ) ,
 		idLocation_( idToken.location( ) ) ,
 		path_( pathToken.stringValue( ) ) ,
@@ -197,7 +197,7 @@ T_TextureInstrNode::T_TextureInstrNode(
 		T_InstrListNode& parent ,
 		T_SRDToken const& idToken ,
 		const E_TexType type ) noexcept
-	: A_InstructionNode( OP_PROGRAM , parent ) ,
+	: A_InstructionNode( OP_PROGRAM , parent , E_InstrRestriction::FRAME ) ,
 		id_( idToken.stringValue( ) ) ,
 		idLocation_( idToken.location( ) ) ,
 		type_( type )
diff --git a/opast.hh b/opast.hh
index a5171e5..1755b07 100644
--- a/opast.hh
+++ b/opast.hh
@@ -76,16 +76,38 @@ class A_Node
 
 /*----------------------------------------------------------------------------*/
 
+// Some instructions are restricted to either the initialisation code or the
+// frame code.
+enum class E_InstrRestriction
+{
+	INIT , FRAME
+};
+using T_InstrRestriction = T_Flags< E_InstrRestriction >;
+
 // Base class for instruction nodes
 class A_InstructionNode : public A_Node
 {
+    private:
+	const T_InstrRestriction restriction_;
+
     protected:
-	A_InstructionNode( E_Type type ,
-			A_Node& parent ) noexcept
-		: A_Node( type , &parent )
-	{}
+	A_InstructionNode( const E_Type type ,
+			A_Node& parent ,
+			T_InstrRestriction restriction = {} ) noexcept
+		: A_Node( type , &parent ) ,
+			restriction_( restriction )
+	{
+		assert( !restriction_.isSet({
+					E_InstrRestriction::INIT ,
+					E_InstrRestriction::FRAME }) );
+	}
+
+    public:
+	T_InstrRestriction restriction( ) const noexcept
+		{ return restriction_; }
 };
 
+
 // Nodes that store lists of instructions
 class T_InstrListNode : public A_Node
 {
@@ -341,14 +363,14 @@ class T_InputInstrNode : public A_InstructionNode
     public:
 	T_InputInstrNode( T_InstrListNode& parent ,
 			T_SRDToken const& tName ) noexcept
-		: A_InstructionNode( OP_INPUT , parent ) ,
+		: A_InstructionNode( OP_INPUT , parent , E_InstrRestriction::FRAME ) ,
 			name_( tName.stringValue( ) ) , nameLocation_( tName.location( ) )
 	{}
 
 	T_InputInstrNode( T_InstrListNode& parent ,
 			T_SRDToken const& tName ,
 			T_SRDToken const& tDefault ) noexcept
-		: A_InstructionNode( OP_INPUT , parent ) ,
+		: A_InstructionNode( OP_INPUT , parent , E_InstrRestriction::FRAME ) ,
 			name_( tName.stringValue( ) ) , nameLocation_( tName.location( ) ) ,
 			defValue_( tDefault.floatValue( ) ) , dvLocation_( tDefault.location( ) )
 	{}
diff --git a/parsercheck.cc b/parsercheck.cc
index 98ffe42..e30495d 100644
--- a/parsercheck.cc
+++ b/parsercheck.cc
@@ -239,30 +239,54 @@ bool checkCalls( T_RootNode& root )
 				}
 				return {};
 			} );
-	enum class E_CallInfo_ {
-		INIT_CHECKED , FRAME_CHECKED ,
-		INIT_CALLED , FRAME_CALLED
-	};
-	using T_CallInfo_ = T_Flags< E_CallInfo_ , uint8_t >;
-	T_CallInfo_ callInfo[ calls.size( ) ];
+	T_InstrRestriction callInfo[ calls.size( ) ];
 
 	callGraphVisitor.visit( root.functionIndex( "*init*" ) ,
 		[&]( uint32_t id , const bool exit ) -> bool {
-			if ( exit || callInfo[ id ] & E_CallInfo_::INIT_CALLED ) {
+			if ( exit || callInfo[ id ] & E_InstrRestriction::INIT ) {
 				return false;
 			}
-			callInfo[ id ] |= E_CallInfo_::INIT_CALLED;
+			callInfo[ id ] |= E_InstrRestriction::INIT;
 			return true;
 		} );
 	callGraphVisitor.visit( root.functionIndex( "*frame*" ) ,
 		[&]( uint32_t id , const bool exit ) -> bool {
-			if ( exit || callInfo[ id ] & E_CallInfo_::FRAME_CALLED ) {
+			if ( exit || callInfo[ id ] & E_InstrRestriction::FRAME ) {
 				return false;
 			}
-			callInfo[ id ] |= E_CallInfo_::FRAME_CALLED;
+			callInfo[ id ] |= E_InstrRestriction::FRAME;
 			return true;
 		} );
 
+	for ( auto i = 0u ; i < root.nFunctions( ) ; i ++ ) {
+		visitor.visit( root.function( i ) ,
+			[&]( A_Node& node , bool exit ) {
+				if ( exit ) {
+					return false;
+				}
+
+				auto const* instr( dynamic_cast< A_InstructionNode const* >( &node ) );
+				if ( instr && ( instr->restriction( ) & callInfo[ i ] ) ) {
+					T_StringBuilder sb;
+					sb << "instruction not allowed in "
+						<< ( ( instr->restriction( ) & E_InstrRestriction::INIT )
+							? "initialisation" : "frame function" );
+					errors.addNew( std::move( sb ) , instr->location( ) );
+				}
+				return true;
+			} );
+	}
+
+	if ( !errors.empty( ) ) {
+		T_StringBuilder sb;
+		for ( auto const& err : errors ) {
+			WriteSRDError( sb , err );
+		}
+		sb << "Parser failed\n" << '\0';
+		fprintf( stderr , "%s" , sb.data( ) );
+		return false;
+	}
+
 	T_StringBuilder sb;
 	for ( auto callerId = 0u ; callerId < calls.size( ) ; callerId ++ ) {
 		const auto nCallees( calls.sizeOf( callerId ) );