diff --git a/Src/java/cql-to-elm/src/main/java/org/cqframework/cql/cql2elm/LibraryBuilder.java b/Src/java/cql-to-elm/src/main/java/org/cqframework/cql/cql2elm/LibraryBuilder.java
index a4fc5efcf..cb8ef899d 100644
--- a/Src/java/cql-to-elm/src/main/java/org/cqframework/cql/cql2elm/LibraryBuilder.java
+++ b/Src/java/cql-to-elm/src/main/java/org/cqframework/cql/cql2elm/LibraryBuilder.java
@@ -2743,6 +2743,22 @@ public Expression applyTargetMap(Expression source, String targetMap) {
             String functionArgument = targetMap.substring(invocationStart + 1, targetMap.lastIndexOf(')'));
             Expression argumentSource =
                     functionArgument.equals("%value") ? source : applyTargetMap(source, functionArgument);
+
+            // NOTE: This is needed to work around the mapping for ToInterval
+            // FHIRHelpers defines multiple overloads of ToInterval, but the type mapping
+            // does not have the type of the source data type.
+            // All the mappings for ToInterval use FHIR.Period, so this is safe to assume
+            // In addition, no other FHIRHelpers functions use overloads (except ToString and ToDateTime,
+            // but those mappings expand the value element directly, rather than invoking the FHIRHelpers function)
+            TypeSpecifier argumentSignature = null;
+            if (this.options.getSignatureLevel() != SignatureLevel.None) {
+                if (qualifiedFunctionName.equals("FHIRHelpers.ToInterval")) {
+                    NamedTypeSpecifier namedTypeSpecifier =
+                            new NamedTypeSpecifier().withName(dataTypeToQName(resolveTypeName("FHIR", "Period")));
+                    argumentSignature = namedTypeSpecifier;
+                }
+            }
+
             if (argumentSource.getResultType() instanceof ListType) {
                 Query query = of.createQuery()
                         .withSource(of.createAliasedQuerySource()
@@ -2752,6 +2768,11 @@ public Expression applyTargetMap(Expression source, String targetMap) {
                         .withLibraryName(libraryName)
                         .withName(functionName)
                         .withOperand(of.createAliasRef().withName("$this"));
+
+                if (argumentSignature != null) {
+                    fr.getSignature().add(argumentSignature);
+                }
+
                 // This doesn't quite work because the US.Core types aren't subtypes of FHIR types.
                 // resolveCall(libraryName, functionName, new FunctionRefInvocation(fr), false, false);
                 query.setReturn(of.createReturnClause().withDistinct(false).withExpression(fr));
@@ -2763,6 +2784,11 @@ public Expression applyTargetMap(Expression source, String targetMap) {
                         .withName(functionName)
                         .withOperand(argumentSource);
                 fr.setResultType(source.getResultType());
+
+                if (argumentSignature != null) {
+                    fr.getSignature().add(argumentSignature);
+                }
+
                 return fr;
                 // This doesn't quite work because the US.Core types aren't subtypes of FHIR types,
                 // or they are defined as System types and not FHIR types
diff --git a/Src/java/cql-to-elm/src/test/java/org/cqframework/cql/cql2elm/TranslationTests.java b/Src/java/cql-to-elm/src/test/java/org/cqframework/cql/cql2elm/TranslationTests.java
index 876205432..cb254e449 100644
--- a/Src/java/cql-to-elm/src/test/java/org/cqframework/cql/cql2elm/TranslationTests.java
+++ b/Src/java/cql-to-elm/src/test/java/org/cqframework/cql/cql2elm/TranslationTests.java
@@ -467,4 +467,38 @@ void abstractClassNotRetrievable() throws IOException {
                 errors.stream().map(Throwable::getMessage).collect(Collectors.toList());
         assertThat(errorMessages, contains("Specified data type DomainResource does not support retrieval."));
     }
+
+    @Test
+    void mappingExpansionsRespectSignatureLevel() throws IOException {
+        // See: https://github.com/cqframework/clinical_quality_language/issues/1475
+        final CqlTranslator translator = TestUtils.runSemanticTest(
+                "MappingExpansionsRespectSignatureLevel.cql", 0, LibraryBuilder.SignatureLevel.Overloads);
+        /*
+        ExpressionDef: EncounterPeriod
+          expression is Query
+            return
+              expression is FunctionRef
+                name FHIRHelpers.ToInterval
+                signature is NamedTypeSpecifier FHIR.Period
+         */
+
+        Library compiledLibrary = translator.getTranslatedLibrary().getLibrary();
+        List<ExpressionDef> statements = compiledLibrary.getStatements().getDef();
+
+        assertThat(statements.size(), is(2));
+        ExpressionDef encounterPeriod = statements.get(1);
+        assertThat(encounterPeriod.getName(), is("EncounterPeriod"));
+        assertThat(encounterPeriod.getExpression(), instanceOf(Query.class));
+        Query query = (Query) encounterPeriod.getExpression();
+        assertThat(query.getReturn().getExpression(), instanceOf(FunctionRef.class));
+        FunctionRef functionRef = (FunctionRef) query.getReturn().getExpression();
+        assertThat(functionRef.getLibraryName(), is("FHIRHelpers"));
+        assertThat(functionRef.getName(), is("ToInterval"));
+        assertThat(functionRef.getSignature(), notNullValue());
+        assertThat(functionRef.getSignature().size(), is(1));
+        assertThat(functionRef.getSignature().get(0), instanceOf(NamedTypeSpecifier.class));
+        NamedTypeSpecifier namedTypeSpecifier =
+                (NamedTypeSpecifier) functionRef.getSignature().get(0);
+        assertThat(namedTypeSpecifier.getName().getLocalPart(), is("Period"));
+    }
 }
diff --git a/Src/java/cql-to-elm/src/test/resources/org/cqframework/cql/cql2elm/MappingExpansionsRespectSignatureLevel.cql b/Src/java/cql-to-elm/src/test/resources/org/cqframework/cql/cql2elm/MappingExpansionsRespectSignatureLevel.cql
new file mode 100644
index 000000000..77752b2ba
--- /dev/null
+++ b/Src/java/cql-to-elm/src/test/resources/org/cqframework/cql/cql2elm/MappingExpansionsRespectSignatureLevel.cql
@@ -0,0 +1,15 @@
+library MappingExpansionsRespectSignatureLevel
+
+// https://github.com/cqframework/clinical_quality_language/issues/1475
+
+using QICore version '4.1.1'
+
+include FHIRHelpers version '4.0.1'
+
+parameter "Measurement Period" Interval<DateTime> default Interval[@2024-01-01T00:00:00.0Z, @2025-01-01T00:00:00.0Z)
+
+context Patient
+
+define EncounterPeriod:
+  [Encounter] E
+    return E.period
\ No newline at end of file